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2. 04/08/15 2
SOLO
Table of Content
Classical Field Theories
Generalized Coordinates
1. Newton’s Laws of Motion
Analytic Dynamics
Work and Energy
Basic Definitions
Constraints
The Stationary Value of a Function and of a Definite Integral
The Principle of Virtual Work
2. D’Alembert Principle
3. Hamilton’s Principle
4. Lagrange’s Equations of Motion
5. Hamilton’s Equations
Introduction to Lagrangian and Hamiltonian Formulation
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj tdtqtqtLCI
Second Method (Carathéodory)
Equivalent Integrals
Hamilton-Jacobi Theory
Theorem of Noether for Single Integral
3. 04/08/15 3
SOLO
Table of Content (continue – 1)
Classical Field Theories
Fermat Principle in Optics
Four-Dimensional Formulation of the Theory of Relativity
Electromagnetic Field
Introduction to Lagrangian and Hamiltonian Formulation for
Continuous Systems and Fields
Transition from a Discrete to Continuous Systems
Extremal of the Functional ( ) ( )∫ ∫
∂
∂
∂
∂
=
2
1
,,,,,
t
t
V
j
k
j
kjk tdVd
tx
xtxtCI
ψψ
ψL
Hamiltonian Formalism
Theorem of Noether for Multiple Integrals
Elasticity
Vibrating String
Vibrating Membrane
Vibrating Beam
Plate Theories
Structural Model of the Solid Body
The Inverse Square Law of Forces
4. 04/08/15 4
SOLO
Table of Content (continue – 2)
Classical Field Theories
Variational Principles of Hydrodynamics
Part I – Lagrange Interpretation
Part II: Euler’s Representation
Part III: Simpler Eulerian Variational Principle
Part IV: Problem of the Motion of Fluid Subjected to Gravity Forces and
Surface Tension Forces
Dynamics of Acoustic Field in Gases
References
Equation of Motion of a Variable Mass System – Lagrangian Approach
5. 5
Analytic DynamicsSOLO
Newton’s Laws of Motion
“The Mathematical Principles of Natural Philosophy” 1687
First Law
Every body continues in its state of rest or of uniform motion in
straight line unless it is compelled to change that state by forces
impressed upon it.
Second Law
The rate of change of momentum is proportional to the force
impressed and in the same direction as that force.
Third Law
To every action there is always opposed an equal reaction.
→
=→= constvF
0
( )vm
td
d
p
td
d
F
==
2112 FF
−=
vmp
= td
pd
F
=
12F
1 2
21F
Return to Table of Content
6. 6
Analytic DynamicsSOLO
Work and Energy
The work W of a force acting on a particle m that moves as a result of this along
a curve s from to is defined by:
F
1r
2r
∫∫ ⋅
=⋅=
•∆ 2
1
2
1
12
r
r
r
r
rdrm
dt
d
rdFW
r
1r
2r
rd
rdr
+
1
2
F
m
s
rd
is the displacement on a real path.
••∆
⋅= rrmT
2
1
The kinetic energy T is defined as:
1212
2
1
2
1
2
1
2
TTrrd
m
dtrr
dt
d
mrdrm
dt
d
W
r
r
r
r
r
r
−=
⋅=⋅
=⋅
= ∫∫∫
⋅
⋅
••••⋅
For a constant mass m
7. 7
Analytic DynamicsSOLO
Work and Energy (continue)
When the force depends on the position alone, i.e. , and the quantity
is a perfect differential
( )rFF
= rdF
⋅
( ) ( )rdVrdrF
−=⋅
The force field is said to be conservative and the function is known as the
Potential Energy. In this case:
( )rV
( ) ( ) ( ) 212112
2
1
2
1
VVrVrVrdVrdFW
r
r
r
r
−=−=−=⋅= ∫∫
∆
The work does not depend on the path from to . It is clear that in a conservative
field, the integral of over a closed path is zero.
12W 1r
2r
rdF
⋅
( ) ( ) 01221
21
1
2
2
1
=−+−=⋅+⋅=⋅ ∫∫∫ VVVVrdFrdFrdF
path
r
r
path
r
rC
Using Stoke’s Theorem it means that∫∫∫ ⋅×∇=⋅
SC
sdFrdF
0=×∇= FFrot
Therefore is the gradient of some scalar functionF
( ) rdrVdVrdF
⋅−∇=−=⋅
( )rVF
−∇=
8. 8
Analytic DynamicsSOLO
Work and Energy (continue)
and
•
→∆→∆
⋅−=⋅−=
∆
∆
= rF
dt
rd
F
t
V
dt
dV
tt
00
limlim
But also for a constant mass system
••••••••••••
⋅=⋅=
⋅+⋅=
⋅= rFrrmrrrr
m
rrm
dt
d
dt
dT
22
1
Therefore for a constant mass in a conservative field
( ) .0 constEnergyTotalVTVT
dt
d
==+⇒=+
Return to Table of Content
9. 9
Analytic DynamicsSOLO
1.4 Basic Definitions
Given a system of N particles defined by their coordinates:
( ) ( ) ( ) ( ) Nkktzjtyitxzyxrr kkkkkkkk ,,2,1,,
=++==
where are the unit vectors defining any Inertial Coordinate Systemkji
,,
The real displacement of the particle mk :
( ) ( ) ( ) Nkktdzjtdyitdxrd kkkk ,,2,1
=++=
is the infinitesimal change in the coordinates along real path caused by all the
forces acting on the particle mk .
The virtual displacements (Δxk , Δyk, Δzk, Δt) are infinitesimal changes in the
coordinates; they are not real changes because they are not caused by real forces.
The virtual displacements define a virtual path that coincides with the real one at
the end points.
10. 10
Analytic DynamicsSOLO
Basic Definitions (continue)
( )trk
( )1trk
( )2trk
krd
1
2
F
km
),,,( dttdzzdyydxxPrdr kkkkkkkk ++++=+
),,,( tzyxP kkk
),,,( ttzzyyxxP kkkkkk ∆+∆+∆+∆+
),,,( tzzyyxxP kkkkkk ∆+∆+∆+
tvrd kk ∆=
i
j
k
True (Dynamical or Newton) Path
Virtual Path
Return to Table of Content
11. 11
Analytic DynamicsSOLO
1.5 Constraints
If the N particles are free the system has n = 3 N degrees of freedom.( ) Nkzyxr kkkk ,,2,1,,
=
The constraints on the system can be of the following types:
(1) Equality Constraints: The general form (the Pffafian form)
( ) ( ) ( )[ ] ( ) mldttradztradytradxtra l
t
N
k
k
l
zkk
l
ykk
l
xk ,,2,10,,,,
1
==+++∑=
or
{ } maaarankmldtarda l
zk
l
yk
l
xk
l
t
N
k
k
l
k ===+⋅∑=
,,,,2,10
1
We can classify the constraints as follows:
(a) Time Dependency
(a1) Catastatic mlal
t ,,2,10 ==
(a2) Acatastatic mlal
t ,,2,10 =≠
(1) Equality Constraints
(2) Inequality Constraints
12. 12
Analytic DynamicsSOLO
Constraints (continue)
Equality Constraints: The general form (the Pffafian form) (continue)
{ } maaarankmldtarda l
zk
l
yk
l
xk
l
t
N
k
k
l
k ===+⋅∑=
,,,,2,10
1
(b) Integrability
(b1) Holonomic if the Pffafian forms are integrable; i.e.:
mldt
t
f
zd
z
f
yd
y
f
xd
x
f
df
N
k
l
k
k
l
k
k
l
k
k
l
l ,,2,1
1
=
∂
∂
+
∂
∂
+
∂
∂
+
∂
∂
= ∑=
or
( ) mltzyxzyxf NNNl ,,2,10,,,,,,, 111 ==
(b2) Non-holonomic if the Pffafian forms are not integrable
(b2.1) Scleronomic:
(b2.2) Rheonomic:
ml
l
t
f
,,2,1
0
=
=
∂
∂
or
( ) mlzyxzyxf NNNl ,,2,10,,,,,, 111 ==
ml
l
t
f
,,2,1
0
=
≠
∂
∂
14. 14
Analytic DynamicsSOLO
Constraints (continue)
Displacements Consistent with the Constraints:
The real displacement consistent with the
General Equality Constraints (Pffafian form) is:
The virtual displacement consistent with the
General Equality Constraints (Pffafian form) is:
dtkdzjdyidxrd kkkk ,
++=
[ ] mldtardadtadzadyadxa l
t
N
k
k
l
k
l
t
N
k
k
l
zkk
l
ykk
l
xk ,,2,10
11
==+⋅=+++ ∑∑ ==
tkzjyixr kkkk ∆∆+∆+∆=∆ ,
[ ] mltaratazayaxa l
t
N
k
k
l
k
l
t
N
k
k
l
zkk
l
ykk
l
xk ,,2,10
11
==∆+∆⋅=∆+∆+∆+∆ ∑∑ ==
Dividing the Pffafian equation by dt and taking the limit, we obtain:
mlraa
N
k
k
l
k
l
t ,,2,1
1
=⋅−= ∑=
⋅
Now replace in the virtual displacement equationl
ta
mltrra
N
k
kk
l
k ,,2,10
1
==
∆−∆⋅∑=
⋅
Define the δ variation as:
td
d
t∆−∆=
∆
δ
15. 15
Analytic DynamicsSOLO
Constraints (continue)
Displacements Consistent with the Constraints (continue):
Define the δ variation as: td
d
t∆−∆=
∆
δ
( )trk
kr
δ
km
),,,( dttdzzdyydxxPrdr kkkkkkkk ++++=+
),,,( tzyxP kkk
),,,( ttzzyyxxP kkkkkk ∆+∆+∆+∆+
),,,( tzzyyxxP kkkkkk ∆+∆+∆+
dtrrd kk
⋅
=
i
j
k
True (Dynamical or Newton) Path
Virtual Path
kr
∆ trr kk ∆=∆
⋅
Then: kkk r
td
d
trr
∆−∆=
∆
δ
From the Figure we can see that δ
variation corresponds to a virtual
displacement in which the time t is
held fixed and the coordinates varied
to the constraints imposed on the
system.
mlra
N
k
k
l
k ,,2,10
1
==⋅∑=
δ
For the Holonomic Constraints: ( ) mltzyxzyxf NNNl ,,2,10,,,,,,, 111 ==
mlrf
N
k
klk ,,2,10
1
==⋅∇∑=
δ
Return to Table of Content
16. 16
Analytic DynamicsSOLO
1.6 Generalized Coordinates
The motion of a mechanical system of N particles is completely defined by n = 3N
coordinates . Quite frequently we may find it more
advantageous to express the motion of the system in terms of a different set of
coordinates, say . If we take in consideration the m constraints we
can reduce the coordinates to n = 3N-m generalized coordinates.
( ) ( ) ( ) ( )Nktztytx kkk ,,2,1,, =
( )T
nqqqq ,,, 21
=
( ) ( ) ( ) ( ) ( ) Nkktqzjtqyitqxtqqqrtqr kkknkk ,,2,1,,,,,,,, 21
=++==
Nkkdzjdyidxdt
t
r
dq
q
r
rd kkk
k
j
n
j j
k
k ,,2,1
1
=++=
∂
∂
+
∂
∂
= ∑=
Nk
t
r
q
q
r
td
rd
rv k
j
n
j j
kk
kk ,,2,1
1
=
∂
∂
+
∂
∂
=== ∑=
⋅
In the same way
Nkkzjyixt
t
r
q
q
r
r kkk
k
j
n
j j
k
k ,,2,1
1
=∆+∆+∆=∆
∂
∂
+∆
∂
∂
=∆ ∑=
and
Nkt
t
r
tq
q
r
t
t
r
q
q
r
trrr k
j
n
j j
kk
j
n
j j
k
kkk ,,2,1
11
==∆
∂
∂
−∆
∂
∂
−∆
∂
∂
+∆
∂
∂
=∆−∆= ∑∑ ==
⋅
δ
17. 17
Analytic DynamicsSOLO
Generalized Coordinates (continue)
( ) Nkq
q
r
tqq
q
r
r
n
j
j
j
k
jj
n
j j
k
k ,,2,1
11
=
∂
∂
=∆−∆
∂
∂
= ∑∑ ==
δδ
where tqqq jjj ∆−∆=
∆
δ
The Generalized Equality Constraints in Generalized Coordinates will be:
mldt
t
r
aadq
q
r
a
dt
t
r
aadq
q
r
adtarda
N
k
kl
k
l
ti
n
i i
k
N
k
l
k
N
k
N
k
kl
k
l
ti
n
i i
kl
k
l
t
N
k
k
l
k
,,2,10
11 1
1 111
==
∂
∂
⋅++
∂
∂
⋅=
=
∂
∂
⋅++
∂
∂
⋅=+⋅
∑∑ ∑
∑ ∑∑∑
== =
= ===
If we define
∑ ∑∑= =
∆
=
∆
∂
∂
⋅+=
∂
∂
⋅=
N
k
N
k
kl
k
l
t
l
t
n
i i
kl
k
l
i
t
r
aac
q
r
ac
1 11
&
we obtain mldtcdqc l
ti
n
i
l
i ,,2,10
1
==+∑=
and the virtual displacements compatible with the constraints are
mlqc i
n
i
l
i ,,2,10
1
==∑=
δ
18. 18
Analytic DynamicsSOLO
Generalized Coordinates (continue)
The number of degrees of freedom of the system is n = 3N-m. However, when the
system is nonholonomic, it is possible to solve the m constraint equations for the
corresponding coordinates so that we are forced to work with a number of
coordinates exceeding the degrees of freedom of the system. This is permissible
provided the surplus number of coordinates matches the number of constraint
equations. Although in the case of a holonomic system it may be possible to solve
for the excess coordinates, thus eliminating them, this is not always necessary or
desirable. If surplus coordinates are used, the corresponding constraint equations
must be retained.
Return to Table of Content
19. 19
Analytic DynamicsSOLO
1.7 The Stationary Value of a Function and of a Definite Integral
In problems of dynamics is often sufficient to find the stationary value of functions
instead of the extremum (minimum or maximum).
Definition:
A function is said to have a stationary value at a certain point if the rate of change in
every direction of the point is zero.
Examples:
(1) ( ) ni
u
f
du
u
f
dfuuuf
i
n
i
i
i
n ,,2,100,,,
1
21 ==
∂
∂
→=
∂
∂
=→ ∑=
By solving those n equations we obtain for which f is
stationary
( )nuuu ,,, 21
20. 20
Analytic DynamicsSOLO
The Stationary Value of a Function and of a Definite Integral
(continue)
Examples (continue):
(2) ( )nuuuf ,,, 21 with the constraints { } marankmldua l
k
N
k
k
l
k ===∑=
,,2,10
1
Lagrange’s multipliers solution gives:
0
1 1
=
+
∂
∂
= ∑ ∑= =
i
n
i
m
l
l
il
i
dua
u
f
df λ
By choosing the m Lagrange’s multipliers λl to annihilate the coefficients of the
m dependent differentials dui we have
equationsmn
mldua
nia
u
f
n
l
i
l
i
m
l
l
il
i
+
==
==+
∂
∂
∑
∑
=
=
,,2,10
,,2,10
1
1
λ
21. 21
Analytic DynamicsSOLO
The Stationary Value of a Function and of a Definite Integral
(continue)
Examples (continue):
(3) The functional ( ) ( )
∫
=
2
1
,,
x
x
dx
xd
xyd
xyxFI
We want to find such that I is stationary, when the end points and
are given.
( )xy ( )1xy ( )2xy
( )xy
( ) ( ) ( ) ( )xxyxyxy ηεδ +=+
( )11, yx
( )22 , yx
x
y
The variation of is( )xy
( ) ( ) ( ) ( ) ( ) ( ) ( ) 021 ==+=+= xxxxyxyxyxy ηηηεδ
and
( ) ( ) ( ) ( ) ( ) ( ) ( )
∫∫
++=
=
2
1
2
1
,,,,
x
x
x
x
dx
xd
xd
xd
xyd
xxyxFdx
xd
xyd
xyxFI
η
εηεε
( ) ( ) +++==
==
2
0
2
2
0
2
1
0 ε
ε
ε
ε
εε
εε
d
d
Id
d
d
Id
II
22. 22
Analytic DynamicsSOLO
The Stationary Value of a Function and of a Definite Integral
(continue)
Examples (continue):
Continue: The functional ( ) ( )
∫
=
2
1
,,
x
x
dx
xd
xyd
xyxFI
The necessary condition for a stationary value is
( ) ( )
( ) ( ) ( )[ ] 0
0
12
0
2
1
2
1
=−
∂
∂
+
∂
∂
−
∂
∂
=
∂
∂
+
∂
∂
=
∫
∫
=
xx
xd
yd
F
dxx
xd
yd
F
xd
d
y
F
dx
xd
xd
xd
yd
F
x
y
F
d
Id
x
x
nintegratio
partsby
x
x
ηηη
η
η
ε ε
Since this must be true for every continuous function η(x) we have
210 xxx
xd
yd
F
xd
d
y
F
≤≤=
∂
∂
−
∂
∂
Euler-Lagrange Differential Equation
By solving this differential equation, y(x),for which I is stationary is found.
JOSEPH-LOUIS
LAGRANGE
1736-1813
LEONHARD EULER
1707-1783
23. 23
Leonhard Euler (1707-1783)
generalized the brothers Bernoulli methods in
“Me tho dus inve nie ndi line as curvas m axim i m inim ive
pro prie tate g aude nte s sive so lutio pro ble m atis
iso pe rim e trici latissim o se nsu acce pti” (“Me tho d fo r
finding plane curve s that sho w so m e pro pe rty o f m axim a
and m inim a”) published in 1744. Euler solved the Ge o de sic
Pro ble m , i.e. the curves of minimum length constrained to lie
on a given surface.
Joseph-Louis Lagrange (1736-1813)
gave the first analytic methods of Calculus of
Variations in
"Essay on a new method of determining the maxima
and minima of indefinite integral formulas" published
in 1760.
Euler-Lagrange Equation:
SOLO
CALCULUS OF VARIATIONS
Return to Table of Content
24. 24
Analytic DynamicsSOLO
1.8 The Principle of Virtual Work
This is a statement of the Static Equation of a mechanical system.
If the system of N particles is in dynamic equilibrium the resultant force on
each
particle is zero; i.e.:
0=iR
0
1
=⋅= ∑=
N
i
ii rRW
δδ
Because of this, for a virtual displacement the Virtual Work of the system
is
ir
δ
If the system is subjected to the constraints:
{ } maaarankmldtarda l
zk
l
yk
l
xk
l
t
N
k
k
l
k ===+⋅∑=
,,,,2,10
1
Then we denote the external forces on particle i by and the constraint’s
forces
by . The resultant force on i is:
iF
iF'
0' =+= iii FFR
25. 25
Analytic DynamicsSOLO
The Principle of Virtual Work (continue)
We want to find the Virtual Work of the constraint forces.
There are two kind of constraints:
(1) The particle i is constrained to move on a definite surface. We assume that the
motion is without friction and therefore the constraint forces must be
normal to the surface. The virtual variation compatible with the
constraint
must be on the surface, therefore .
iF
ir
δ
0' =⋅ ii rF
δ
ir
δ
iF'
(2) The particle i is acting on the particle j and the distance between them is l(t). .
iF'
i j
jF'
ir
jr
( )tl
26. 26
Analytic DynamicsSOLO
The Principle of Virtual Work (continue)
( ) ( ) ( )tlrrrr jiji
2
=−⋅−
( ) ( ) tllrrrr jiji ∆=∆−∆⋅−
( ) llrrrr jiji
=
−⋅−
⋅⋅
( )
( ) ( ) ji
rr
jiji
jjiiji
rrrrrr
trrtrrrr
ji
δδδδ =→=−⋅−→
→=
∆−∆−
∆−∆⋅−
≠
⋅⋅
0
0
ji FF ''
−=
If we compute the virtual variation and differential and we multiply the second
equation by and add to the first we obtaint∆−
Because is a real (not a generalized) force we can use Newton’s Third Law: i.e.:iF'
and the virtual work of the constraint forces of this system is:
( ) 0''''' =⋅−+⋅=⋅+⋅= rFrFrFrFW iijjii
δδδδδ
We can generalized this by saying that:
0'
1
=⋅∑=
N
i
ii rF
δ
The work done by the constraint forces in virtual displacements compatible with
the constraints (without dissipation) is zero.
27. 27
Analytic DynamicsSOLO
The Principle of Virtual Work (continue)
From equation we obtain:0' =+= iii FFR
∑∑∑∑ ====
⋅=⋅+⋅=⋅=
N
i
ii
N
i
ii
N
i
ii
N
i
ii rFrFrFrR
1
0
111
'0
δδδδ
or
0
1
=⋅= ∑=
N
i
ii rFW
δδ
The Principle of Virtual Work
The work done by the applied forces in infinitesimal virtual displacements compatible
with the constraints (without dissipation) is zero
28. 28
Analytic DynamicsSOLO
The Principle of Virtual Work (continue)
{ } mjNimaaarank
mjra
j
zi
j
yi
j
xi
N
k
k
j
k
,,2,1&,,1,,
,,2,10
1
===
==⋅∑=
δ
We found that the General Equality Constraint the virtual displacement
compatible with the constraint must be:
ir
δ
Let adjoin the m constraint equations by the m Lagrange’s multipliers and add to the
virtual work equation:
jλ
0
1 11 11
=⋅
+=
⋅+⋅= ∑ ∑∑ ∑∑ = == ==
N
i
i
m
j
j
iji
m
j
N
i
i
j
ij
N
i
ii raFrarFW
δλδλδδ
There are 3N virtual displacements from which m are dependent of the constraint
relations and 3N-m are independent. We will choose the m Lagrange’s multipliers
to annihilate the coefficients of the m dependent variables:
jλ
−+=
=
=+ ∑= iationsmNtindependenNmi
mtheofbecausemi
aF
j
m
j
j
iji
var33,,1
,,2,1
0
1
λ
λ
29. 29
Analytic DynamicsSOLO
The Principle of Virtual Work (continue)
From we obtain:0' =+= iii FFR
∑=
=
m
j
j
iji aF
1
'
λ
where are chosen such thatjλ mjforaF
m
j
j
iji ,,2,10
1
==+ ∑=
λ
Since , we obtain:k
n
k k
i
i q
q
r
r δδ ∑= ∂
∂
=
1
0
1 1 11
1 111 1
=
∂
∂
+
∂
∂
=
=
∂
∂
⋅
+=⋅
+=
∑ ∑ ∑∑
∑ ∑∑∑ ∑
= = ==
= === =
n
k
k
m
j
N
i k
ij
ij
N
i k
i
i
N
i
n
k
k
k
i
m
j
j
iji
N
i
i
m
j
j
iji
q
q
r
a
q
r
F
q
q
r
aFraFW
δλ
δλδλδ
We define:
nk
q
r
FQ
N
i k
i
ik ,,2,1
1
=
∂
∂
=∑=
∆
nkc
q
r
aQ
m
j
j
kj
m
j
N
i k
ij
ijk ,,2,1'
11 1
==
∂
∂
= ∑∑ ∑ == =
∆
λλ nk
q
r
ac
N
i k
ij
i
j
k ,,2,1
1
=
∂
∂
=∑=
∆
Generalized Forces
Generalized Constraint Forces
Return to Table of Content
30. 30
Analytic DynamicsSOLO
2. D’Alembert Principle
Jean Le Rond
d’ Alembert
1717-1783
Newton’s Second Law for a particle of mass and a linear momentum
vector can be written as
im
iii vmp
=
D’Alembert Principle: 0' =−+
•
iii pFF
D’Alembert Principle enables us to trait dynamical problems as if they
were statical.
Let extend the Principle of Virtual Work to dynamic systems:
0'
1
=⋅
−+∑=
•N
i
iiii rpFF
δ
Assuming that the constraints are without friction the virtual work of the constraint
force is zero . Then we have
Generalized D’Alembert Principle: 0
1
=⋅
−∑=
•N
i
iii rpF
δ
0'
1
=⋅∑=
N
i
ii rF
δ
The Generalized D’Alembert Principle
The total Virtual Work performed by the effective forces through infinitesimal Virtual
Displacement, compatibile with the system constraints are zero.
0=−
•
ii pF
is the effective force.
“Traité de
Dynamique”
1743
Return to Table of Content
where and are the applied and constraint forces, respectively.iF
iF'
31. 31
Analytic DynamicsSOLO
3. Hamilton’s Principle
William Rowan
Hamilton
1805-1865
Let write the D’Alembert Principle: in integral form0
1
=⋅
−∑=
•N
i
iii rpF
δ
0
2
1
1
=⋅
−∫∑=
•
t
t
N
i
iii dtrpF
δ
But
( )∑∑∑ ===
•
⋅+
⋅−=⋅−
N
i
iii
N
i
iii
N
i
iii r
td
d
vmrvm
td
d
rvm
111
δδδ
Let find ( )ir
td
d
δ
iiiii r
td
d
ttvrr
∆−∆=∆−∆=δ are the virtual displacements compatible with the
constraints mjra
N
i
i
j
i ,,2,10
1
==⋅∑=
δ
( )tri
ir
δ
tvi ∆
( )tPi( )tP i'
( )ttP i ∆+'
ir
∆
Virtual Path True Path (P)
Newtonian or
Dynamic Path
The Constraint
Space at t
mjra
N
i
i
j
i ,,10
1
==⋅∑=
δ
( ) ( )
( ) ( )
( ) ( )
=∆=∆
=∆=∆
==
0
0
0
21
21
21
tttt
trtr
trtr
ii
ii
δδ
1t
2t
32. 32
Analytic DynamicsSOLO
Hamilton’s Principle (continue)
Since
td
rd
vv i
Pi i
==
( )
( )
( )
t
td
d
vr
td
d
vt
td
d
r
td
d
v
t
td
d
r
td
d
td
rd
tdtd
rdrd
ttd
rrd
vvv
iiiii
i
i
iiii
ttPii i
∆−∆+≈
∆−
∆+≈
∆+
∆+
=
=
∆+
∆+
=
∆+
∆+
==∆+ ∆+
1
1
'
( ) ( ) tar
td
d
tatvr
td
d
t
td
d
vr
td
d
v iiiiiiii ∆+=∆+∆−∆=∆−∆=∆
δ
Therefore
( ) ( )
ecommutativare
td
d
and
r
td
d
vv
td
d
ttavr
td
d
iiiiii
δ
δδδ
→
→==
∆−∆=∆−∆=
33. 33
Analytic DynamicsSOLO
Hamilton’s Principle (continue)
Now we can develop the expression:
tavmvvmrvm
td
d
ram
N
i
iii
N
i
iii
N
i
iii
N
i
iii ∆⋅−
∆⋅+
⋅−=⋅− ∑∑∑∑ ==== 1111
δδ
But the Kinetic Energy T of the system is:
∑=
⋅=
N
i
iii vvmT
12
1
∑=
∆⋅=∆
N
i
iii vvmT
1
∑∑∑ ===
⋅
⋅=⋅=⋅=
N
i
iii
N
i
iii
N
i
iii vFmavmvvmT
111
Therefore
Trvm
td
d
tTTrvm
td
d
ram
N
i
iii
N
i
iii
N
i
iii
δδ
δδ
+
⋅−=
=∆−∆+
⋅−=⋅−
∑
∑∑
=
•
==
1
11
34. 34
Analytic DynamicsSOLO
Hamilton’s Principle (continue)
From the integral form of D’Alembert Principle we have:
( )
∫ ∑∫ ∑∑
∫ ∑∫ ∑
∫∑
⋅+=
⋅++⋅−=
=
⋅++
⋅−=
=⋅+−=
===
==
=
2
1
2
1
2
1
2
1
2
1
2
1
111
0
11
1
0
t
t
N
i
ii
t
t
N
i
ii
N
i
t
tiii
t
t
N
i
ii
t
t
N
i
iii
t
t
N
i
iiii
dtrFTdtrFTrvm
dtrFTdtrvm
td
d
dtrFam
δδδδδ
δδδ
δ
We obtained
( ) 0
2
1
2
1
1
=+=
⋅+ ∫∫ ∑=
dtWTdtrFT
t
t
t
t
N
i
ii δδδ
Extended Hamilton’s Principle
35. 35
Analytic DynamicsSOLO
Hamilton’s Principle (continue)
If we develop and we can writetTTT ∆−∆= δ tvrr iii ∆−∆=
δ
0
2
1
2
1
111
=
∆
⋅+−
∆⋅+∆=
⋅+ ∫ ∑∑∫ ∑ ===
dttvFTrFTdtrFT
t
t
N
i
ii
N
i
ii
t
t
N
i
ii
δδ
and because ∑=
⋅=
N
i
ii vFT
1
02
2
1
1
=
∆−
∆⋅+∆∫ ∑=
dttTrFT
t
t
N
i
ii
The pair and is arbitrary but compatible with the constraints:ir
∆ t∆
mjtara j
t
N
i
i
j
i ,,2,10
1
==∆+∆⋅∑=
36. 36
Analytic DynamicsSOLO
Hamilton’s Principle (continue)
For a Conservative System VF ii −∇=
VrVrFW
N
i
ii
N
i
ii δδδδ −=⋅∇−=⋅= ∑∑ == 11
We have ( ) ( ) 0
2
1
2
1
2
1
==−=+ ∫∫∫
t
t
t
t
t
t
dtLdtVTdtWT δδδ
where WTVTL +=−=
∆
=−∇=−==
∆
∫ NiVFVTLdtL ii
t
t
,,2,1;0
2
1
δ
Hamilton’s Principle
for
Conservative Systems
Hamilton’s Principle for Conservative Systems:
The actual path of a conservative system in the configuration space renders
the value of the integral stationary with respect to all arbitrary
variations (compatible with the constraints) of the path between the two
instants and provided that the path variations vanish at those two points.
∫=
2
1
t
t
dtLI
1t 2t
Return to Table of Content
37. 37
Analytic DynamicsSOLO
4. Lagrange’s Equations of Motion
Joseph Louis
Lagrange
1736-1813
“Mecanique
Analitique”
1788
The Extended Hamilton’s Principle states: 0
2
1
1
=
⋅+∫ ∑=
dtrFT
t
t
N
i
ii
δδ
where are the virtual displacements compatible with the
constraints:
ir
δ
mjqcq
q
r
ara
n
k
k
k
i
n
k
k
N
i k
ij
i
N
i
i
j
i ,,2,10
11 11
===
∂
∂
=⋅ ∑∑ ∑∑ == ==
δδδ
T the kinetic energy of the system is given by:
∑ ∑∑∑ =
⋅
===
⋅⋅
=
∂
∂
+
∂
∂
⋅
∂
∂
+
∂
∂
=⋅=
N
j
n
i
j
i
i
j
n
i
j
i
i
j
j
N
j
jjj tqqT
t
r
q
q
r
t
r
q
q
r
mrrmT
1 111
,,
2
1
2
1
where is the vector of generalized coordinates.( )nqqqq ,,, 21
=
−∆
∂
∂
+
∆
∂
∂
+∆
∂
∂
+
=
−
∆+∆+∆+=∆
⋅
=
⋅⋅⋅⋅
∑ tqqTt
t
T
q
q
T
q
q
T
tqqTtqqTttqqqqTT
n
i
i
i
i
i
,,,,,,,,
1
t
T
q
q
T
q
q
T
T
n
i
i
i
i
i ∂
∂
+
∂
∂
+
∂
∂
= ∑=1
( ) ( ) ∑∑ ==
∂
∂
+
∂
∂
=
∆−∆
∂
∂
+∆−∆
∂
∂
=∆−∆=
n
i
i
i
i
i
n
i
ii
i
ii
i
q
q
T
q
q
T
tqq
q
T
tqq
q
T
tTTT
11
δδδ
38. 38
Analytic DynamicsSOLO
Lagrange’s Equations of Motion (continue)
( ) ( ) ∑∑ ==
∂
∂
+
∂
∂
=
∆−∆
∂
∂
+∆−∆
∂
∂
=∆−∆=
n
i
i
i
i
i
n
i
ii
i
ii
i
q
q
T
q
q
T
tqq
q
T
tqq
q
T
tTTT
11
δδδ
But because δ and are commutative and:td
d
( )ii q
dt
d
q δδ =
∑=
∂
∂
+
∂
∂
=
n
i
i
i
i
i
q
dt
d
q
T
q
q
T
T
1
δδδ
This is an expected result because the variation δ keeps the time t constant.
We found that , therefore∑= ∂
∂
=
n
i
i
i
j
j q
q
r
r
1
δδ
∫∑∫∑ ∑∫ ∑ ∑∫ ∑ == == ==
=
∂
∂
⋅=
∂
∂
⋅=
⋅
2
1
2
1
2
1
2
1
11 11 11
t
t
n
i
ii
t
t
n
i
i
N
j i
j
j
t
t
N
j
n
i
i
i
j
j
t
t
N
j
jj dtqQdtq
q
r
Fdtq
q
r
FdtrF δδδδ
where ForcesdGeneralizeni
q
r
FQ
N
j i
j
ji ,,2,1
1
=
∂
∂
⋅=∑=
∆
Now
( )
∫∑∑
∫∑∫ ∑
==
==
−
∂
∂
−
∂
∂
−
∂
∂
=
+
∂
∂
+
∂
∂
=
⋅+=
2
1
2
1
2
1
2
1
11
0
.int
11
0
t
t
n
i
iii
i
i
i
n
i
t
ti
i
partsby
t
t
n
i
iii
i
i
i
t
t
N
j
jj
dtqQq
q
T
q
q
T
td
d
q
q
T
dtqQq
q
T
q
td
d
q
T
dtrFT
δδδδ
δδδδδ
39. 39
Analytic DynamicsSOLO
Lagrange’s Equations of Motion (continue)
0
2
1
1
=
−
∂
∂
−
∂
∂
∫∑=
t
t
i
n
i
i
ii
dtqQ
q
T
q
T
td
d
δ
where the virtual displacements must be consistent with the constraints
. Let adjoin the previous equations by the constraints multiplied
by the Lagrange’s multipliers
iqδ
mkqc
n
i
i
k
i ,,2,10
1
==∑=
δ
( )mkk ,,2,1 =λ
0
1 11 1
=
=
∑ ∑∑ ∑ = == =
n
i
i
m
k
k
ik
m
k
n
i
i
k
ik qcqc δλδλ
to obtain
0
2
1
1 1
=
−−
∂
∂
−
∂
∂
∫∑ ∑= =
t
t
i
n
i
m
k
k
iki
ii
dtqcQ
q
T
q
T
td
d
δλ
While the virtual displacements are still not independent, we can chose the
Lagrangian’s multipliers so as to render the bracketed coefficients of
equal to zero. The remaining being independent can be chosen
arbitrarily, which leads to the conclusion that the coefficients of
are zero. It follows
iqδ
iqδ
( )mkk ,,2,1 =λ
( )nmiqi ,,2,1 +=δ
( )miqi ,,2,1 =δ
nicQ
q
T
q
T
dt
d m
k
k
iki
ii
,,2,1
1
=+=
∂
∂
−
∂
∂
∑=
λ
40. 40
Analytic DynamicsSOLO
Lagrange’s Equations of Motion (continue)
nicQ
q
T
q
T
dt
d m
k
k
iki
ii
,,2,1
1
=+=
∂
∂
−
∂
∂
∑=
λ
We have here n equations with n+m unknowns . To find all the
unknowns we must add the m equations defined by the constraints, to obtain
( ) ( ) mn tqtq λλ ,,,,, 11
nicQ
q
T
q
T
dt
d m
k
k
iki
ii
,,2,1
1
=+=
∂
∂
−
∂
∂
∑=
λLagrange’s Equations:
mkcqc k
t
n
i
i
k
i ,,2,10
1
==+∑=
Let define
Generalized Constraint Forces: nicQ
m
k
k
iki ,,2,1'
1
== ∑=
λ
41. 41
Analytic DynamicsSOLO
Lagrange’s Equations of Motion (continue)
If the system is acted upon by some forces which are derivable from a potential
function and some forces which are not, we can write:( ) ( )nn qqqVrrrV ,,,,,, 2121
−=− n
jF
n
jjj FVF
+−∇=
( ) ∑∑ ∑∑ ∑∑ == == ==
=
∂
∂
⋅+
∂
∂
⋅∇−=
∂
∂
⋅+∇−=⋅
n
i
ii
n
i
i
N
j i
jn
j
i
j
j
N
j
n
i
i
i
jn
jj
N
j
jj qQq
q
r
F
q
r
Vq
q
r
FVrF
11 11 11
δδδδ
But where∑= ∂
∂
⋅∇=
∂
∂ N
j i
j
j
i q
r
V
q
V
1
k
z
V
j
y
V
i
x
V
V
jjj
j
∂
∂
+
∂
∂
+
∂
∂
=∇
Therefore:
niQ
q
V
q
r
F
q
r
VQ in
i
N
j i
jn
j
N
j i
j
ji ,,2,1
11
=+
∂
∂
−=
∂
∂
⋅+
∂
∂
⋅∇−= ∑∑ ==
Generalized External Forces:
Generalized External Nonconservative Forces:
ni
q
r
FQ
N
j i
jn
jin ,,2,1
1
=
∂
∂
⋅=∑=
∆
42. 42
Analytic DynamicsSOLO
Lagrange’s Equations of Motion (continue)
The Lagrange’s Equations nicQ
q
T
q
T
dt
d m
k
k
iki
ii
,,2,1
1
=+=
∂
∂
−
∂
∂
∑=
λ
Define: ( ) ( ) ( )qVtqqTtqqL
−=
∆
,,,,
Because we assume that , we have( ) i
q
qV
i
∀=
∂
∂
0
Lagrange’s Equations: nicQ
q
L
q
L
dt
d m
k
k
ikin
ii
,,2,1
1
=+=
∂
∂
−
∂
∂
∑=
λ
mkcqc k
t
n
i
i
k
i ,,2,10
1
==+∑=
We proved
=−∇=−==
∆
∫ NiVFVTLdtL ii
t
t
,,2,1;0
2
1
δ
Hamilton’s Principle for Conservative Systems
Lagrange’s Equations for a Conservative System without Constraints:
( )0,,,,2,10 =−=−∇===
∂
∂
−
∂
∂ k
iii
ii
cVTLVFni
q
L
q
L
dt
d
If they are no constraints, from the Lagrange’s Equations, or from Euler-
Lagrange Equation for a stationary solution of , we obtain:∫=
2
1
t
t
dtLI
43. Analytic DynamicsSOLO
Lagrange’s Equations of Motion (continue)
The Lagrangian gives unique Euler-Lagrange Equations, but the inverse is not true,
there more than one Lagrangian that gives the same Euler-Lagrange Equations.
Example 1:
( ) ( ) ( )
td
tqqd
tqqLtqqL
,,
,,:,,1
Φ
+=
( ) ( ) ( ) ( )
( )∫∫∫∫ =
∂
Φ∂
+
∂
Φ∂
+=Φ+=
1
0
1
0
1
0
1
0
1
0
1
0
1
0
,,,,,,,,:,,
00
1
t
t
t
t
t
t
t
t
t
t
t
t
t
t
tdtqqLq
q
q
q
tdtqqLtqqtdtqqLtdtqqL
δδδδδδδ
Example 2:
This is not the most general case
( ) ( ) [ ]2
2
2
1
2
2
2
1221211
2
1
:,,&:,, qqqqtqqLqqqqtqqL −−+=−=
=−=
∂
∂
−
∂
∂
=−=
∂
∂
−
∂
∂
0
0
11
2
1
2
1
22
1
1
1
1
qq
q
L
q
L
dt
d
qq
q
L
q
L
dt
d
=−=
∂
∂
−
∂
∂
=−=
∂
∂
−
∂
∂
0
0
22
2
2
2
2
11
1
2
1
2
qq
q
L
q
L
dt
d
qq
q
L
q
L
dt
d
Return to Table of Content
44. 44
Analytic DynamicsSOLO
5. Hamilton’s Equations
The Lagrange’s Equations nicQ
q
T
q
T
dt
d m
k
k
iki
ii
,,2,1
1
=+=
∂
∂
−
∂
∂
∑=
λ
can be rewritten as:
nicQ
q
T
tq
T
q
qq
T
q
qq
T
q
T
dt
d m
k
k
iki
i
n
i i
j
ji
j
jii
,,2,1
11
222
=++
∂
∂
=
∂∂
∂
+
∂∂
∂
+
∂∂
∂
=
∂
∂
∑∑ ==
λ
therefore consist of a set of n simultaneous second-order differential equations.
They must be solved tacking in consideration the m constraint equations.
mkcqc k
t
n
i
i
k
i ,,2,10
1
==+∑=
A procedure for the replacement of the n second-order partial-differential equations by
2n first-order ordinary-differential equations consists of formulating the problem in
terms of 2n Hamilton’s Equations.
We define first: General Momentum: ni
q
T
p
i
i ,,2,1
=
∂
∂
=
∆
We want to find the transformation from the set of variables to the set
by the Legendre’s Dual Transformation.
( )tqq ,,
( )tpq ,,
45. 45
Analytic DynamicsSOLO
Hamilton’s Equations (continue)
Legendre’s Dual Transformation.
Adrien-Marie
Legendre
1752-1833
Let consider a function of n variables , m variables and time t.ix iy
( )tyyxxF mn ,,,,,, 11
and introduce a new set of variables defined by the transformation:iu
ni
x
F
u
i
i ,,2,1 =
∂
∂
=
∆
We can see that:
∂∂
∂
∂∂
∂
∂∂
∂
∂∂
∂
+
∂
∂
∂∂
∂
∂∂
∂
∂
∂
=
m
mnn
m
n
nn
n
n dy
dy
dy
yx
F
yx
F
yx
F
yx
F
dx
dx
dx
x
F
xx
F
xx
F
x
F
du
du
du
2
1
2
1
2
1
2
11
2
2
1
2
2
1
2
1
2
2
1
2
2
1
We want to replace the variables by the new variables .
We can see that the new n variables are independent if the Hessian Matrix
is nonsingular.
( )nidxi ,,2,1 = ni
njji xx
F
,,1
,,1
2
=
=
∂∂
∂
46. 46
Analytic DynamicsSOLO
Hamilton’s Equations (continue)
Legendre’s Dual Transformation (continue-1)
Let define a new function G of the variables , and t.iu iy
( )tyyuuGFxuG mn
n
i
ii ,,,,,, 11
1
=−=∑=
∆
Then:
( )
dt
t
F
dy
y
F
dx
x
F
udux
dt
t
F
dy
y
F
dx
x
F
dxuduxdG
m
j
j
j
n
i
i
i
iii
n
i
m
j
j
j
i
i
n
i
iiii
∂
∂
−
∂
∂
−
∂
∂
−+=
=
∂
∂
−
∂
∂
−
∂
∂
−+=
∑∑
∑ ∑∑
==
= ==
11
0
1 11
But because: ( )tyyuuGG mn ,,,,,, 11 =
dt
t
G
dy
y
G
du
u
G
dG
n
i
m
j
j
j
i
i ∂
∂
+
∂
∂
+
∂
∂
= ∑ ∑= =1 1
Because all the variations are independent we have:
t
F
t
G
mj
y
F
y
G
ni
u
G
x
jji
i
∂
∂
−=
∂
∂
=
∂
∂
−=
∂
∂
=
∂
∂
= ;,,1;,,1
47. 47
Analytic DynamicsSOLO
Hamilton’s Equations (continue)
Legendre’s Dual Transformation (continue-2)
Now we can define the Dual Legendre’s Transformation from
( )tyyxxF mn ,,,,,, 11 ( ) FxutyyuuG
n
i
iimn −= ∑=1
11 ,,,,,, to
by using
ni
x
F
u
i
i ,,2,1 =
∂
∂
=
ni
u
G
x
i
i ,,2,1 =
∂
∂
=
End of Legendre’s Dual Transformation
48. 48
Analytic DynamicsSOLO
Hamilton’s Equations (continue)
Following the same pattern to find the transformation from the set of variables
to the set , we introduce the Hamiltonian:( )tqq ,, ( )tpq ,,
( )tqqTqpH
n
i
ii ,,
1
−=∑=
∆
where
ni
q
T
p
i
i ,,2,1
=
∂
∂
=
Then
( )tpqHH ,,
=
dt
t
H
dp
p
H
dq
q
H
dt
t
T
dq
q
T
dpq
dt
t
T
dq
q
T
qd
q
T
qdpdpqdH
n
i
i
i
i
i
n
i
i
i
ii
n
i
i
i
i
i
iiii
∂
∂
+
∂
∂
+
∂
∂
=
∂
∂
−
∂
∂
−=
=
∂
∂
−
∂
∂
−
∂
∂
−+=
∑∑
∑
==
=
11
1
and
0
1
=
∂
∂
+
∂
∂
+
−
∂
∂
+
∂
∂
+
∂
∂
∑=
dt
t
T
t
H
dpq
p
H
dq
q
T
q
Hn
i
ii
i
i
ii
49. 49
Analytic DynamicsSOLO
Hamilton’s Equations (continue)
If the Hessian Matrix is nonsingular, all the are independent,
but not the that must be consistent with the constraints:
ni
njji qq
T
,,1
,,1
2
=
=
∂∂
∂
( )nidpi ,,2,1 =
( )nidqi ,,2,1 =
mjdtcdqc j
t
n
i
i
j
i ,,2,10
1
==+∑=
Let adjoin the previous equations by the constraint equations multiplied by the m
Lagrange’s multipliers :j'λ
0'''
11 11 1
=+
=
+ ∑∑ ∑∑ ∑ == == =
m
j
j
ij
n
i
i
m
j
j
ij
m
j
j
t
n
i
i
j
ij dtcdqcdtcdqc λλλ
We have
0''
11 1
=
+
∂
∂
+
∂
∂
+
−
∂
∂
+
+
∂
∂
+
∂
∂
∑∑ ∑ == =
dtc
t
T
t
H
dpq
p
H
dqc
q
T
q
H m
j
j
tj
n
i
ii
i
i
m
j
j
ij
ii
λλ
50. 50
Analytic DynamicsSOLO
Hamilton’s Equations (continue)
By proper choosing the m Lagrange’s multipliers λ’j ,the remainder differentials
and dt are independent and therefore we have:ii dpdq ,
ni
c
t
H
t
T
c
q
H
q
T
p
H
q
m
j
j
tj
m
j
j
ij
ii
i
i
,,2,1
'
'
1
1
=
−
∂
∂
−=
∂
∂
−
∂
∂
−=
∂
∂
∂
∂
=
∑
∑
=
=
λ
λ Legendre’s Dual Transformation
By differentiating the General Momentum Equation and using Lagrange’s
Equations we obtain:
( )∑∑ ==
−++
∂
∂
−=++
∂
∂
=
∂
∂
=
m
j
j
ijji
i
m
j
j
iji
ii
i cQ
q
H
cQ
q
T
q
T
dt
d
p
11
''''' λλλ
ni
cQ
q
H
p
p
H
q
m
j
j
iji
i
i
i
i
,,2,1
1
=
++
∂
∂
−=
∂
∂
=
∑=
λ
mkcqc k
t
n
i
i
k
i ,,2,10
1
==+∑=
Extended Hamilton’s Equations
Constrained Differential Equations
51. 51
Analytic DynamicsSOLO
Hamilton’s Equations (continue)
For Holonomic Constraints (constraints of the form )
we can (theoretically) reduce the number of generalized coordinates to n-m and we
can assume that and n represents the number of degrees of freedom of the system
(this reduction is not possible for Nonholonomic Constraints). Then:
( ) mjtqqf nj .,10,,,1 ==
0== j
t
j
i cc
ni
Q
q
H
p
p
H
q
i
i
i
i
i
,,2,1
=
+
∂
∂
−=
∂
∂
=
Extended Hamilton’s Equations for
Holonomic Constraints
ni
q
V
Q
i
i ,,2,1 =
∂
∂
−=
( ) ( ) ( )qVtqqTtqqL
−=
∆
,,,,
ni
q
L
q
T
p
ii
i ,,2,1
=
∂
∂
=
∂
∂
=
Extended Hamilton’s Equations for
Holonomic Constraints
and a
Conservative System
Conservative
System
52. 52
Analytic DynamicsSOLO
Hamilton’s Equations (continue)
Define:
Hamiltonian for
Conservative Systems
( ) ( ) ( ) ( )qVtqqTtqqLqptqqH
n
i
ii
−=−=∑=
∆
,,,,,,
1
Hamilton’s Canonical Equations
for
Conservative Systems
with
Holonomic Constraints
ni
q
H
p
p
H
q
i
i
i
i
,,2,1
=
∂
∂
−=
∂
∂
=
We have:
Return to Table of Content
53. 04/08/15 53
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Second Method (Carathéodory)
Constantin Carathéodory
(1873-1950)
Carathéodory developed another approach to the
Euler-Lagrange Equations
( ) ( )
Covariant
k
l
l
jj
k
jj
k
q
q
q
qqtL
q
qqtL
p
∂
∂
∂
∂
=
∂
∂
=
,,,,
:Define Canonical Momentum
We assume that is a one to one correspondence between the n
components of pj and the n components of and from the
definition of pk (by the Inverse Function Theorem) we have
j
q
( )k
kjj
pqtx ,,φ=
From we see that the
one to one correspondence is possible only if
( ) ( ) ( ) td
tq
qqtL
qd
qq
qqtL
qd
qq
qqtL
pd k
jj
j
jk
jj
j
jk
jj
k
∂∂
∂
+
∂∂
∂
+
∂∂
∂
=
,,,,,,
:
222
( ) 0
,,
det
2
≠
∂∂
∂
jk
jj
qq
qqtL
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj tdtqtqtLCI
54. 04/08/15 54
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Second Method (Carathéodory)
( ) ( )
k
l
l
jj
k
jj
k
q
q
q
qqtL
q
qqtL
p
∂
∂
∂
∂
=
∂
∂
=
,,,,
: Canonical Momentum
( )k
jj
ptq ,φ=
Define ( ) ( )[ ] ( )k
j
ji
kk
k
k
ptpptqtLpqtH ,,,,:,, φφ +−= Hamiltonian
Let compute
j
q
q
L
p
j
j
k
k
j
k
k
j
qq
p
p
p
q
q
L
p
H
kk
kk
φ
φ =
∂
∂
=
=+
∂
∂
+
∂
∂
∂
∂
−=
∂
∂
j
q
L
p
jjjjjj
q
L
q
p
qq
L
q
L
q
H
jj
∂
∂
−=
∂
∂
+
∂
∂
∂
∂
−
∂
∂
−=
∂
∂ ∂
∂
=
φφ
t
L
t
p
t
q
q
L
t
L
t
H
kk
kk
q
q
L
p
j
j
j
j
∂
∂
−=
∂
∂
+
∂
∂
∂
∂
−
∂
∂
−=
∂
∂ =
∂
∂
=
φ
φ
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj tdtqtqtLCI
William Rowan
Hamilton
1805-1865
55. 04/08/15 55
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Second Method (Carathéodory)
( )
k
jj
k
q
qqtL
p
∂
∂
=
,,
: Canonical Momentum
( ) ( )[ ] ( )k
j
ji
kk
k
k
ptpptqtLpxtH ,,,,:,, φφ +−= Hamiltonian
j
j
q
p
H
=
∂
∂
jj
q
L
q
H
∂
∂
−=
∂
∂
t
L
t
H
∂
∂
−=
∂
∂
Let compute ( ) j
j
jjj
q
H
td
pd
q
L
q
L
td
d
LE
∂
∂
+=
∂
∂
−
∂
∂
=
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj tdtqtqtLCI
Return to Table of Content
56. 04/08/15 56
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Equivalent Integrals
Given a Scalar S = S (t,qk
) є C2
. Along a curve
C: qj
= qj
(t) we can form the Total Derivative:
j
j
q
q
S
t
S
td
Sd
∂
∂
+
∂
∂
=
With the aid of this Scalar ,S, we may construct an alternative Lagrangian by writing
( ) ( )( ) ( ) ( )( ) ( ) ( )( ) ( )( )
td
tqtSd
tqtqtLcq
q
S
t
S
tqtqtLctqtqtL
j
jjk
k
jjjj ,
,,,,:,,*
−=
∂
∂
−
∂
∂
−=
We obtain a new Integral
( ) ( ) ( )( ) ( ) ( )( ) ( ) ( )12
** 2
1
2
1
,,,, SSCIctd
td
Sd
tqtqtLctdtqtqtLCI
t
t
jj
t
t
jj
−−=
−== ∫∫
( ) ( ) 21
*
SSCIcCI −=−
where c > 0 is a constant.
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj tdtqtqtLCI
57. 04/08/15 57
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Equivalent Integrals
Alternative Lagrangian
( ) ( )( ) ( ) ( )( ) ( )( )
td
tqtSd
tqtqtLctqtqtL
j
jjjj ,
,,:,,*
−=
( ) ( ) ( )( ) ( ) ( )12
** 2
1
,, SSCIctdtqtqtLCI
t
t
jj
−−== ∫
We obtain
That is independent of the choice of the curve C joining the points P1 and P2.
It follows that C will be an extremal of the integral I* , if and only if, it is an
extremal of the integral I. Accordingly I and I* are called Equivalent Integrals.
( ) ( ) 21
*
SSCIcCI −=−
Therefore the Lagrangian that gives the Equations of Motions is not necessarily
L = T – V but it can be any function L* = c (T – V) – dS/dt.
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj tdtqtqtLCI
58. 04/08/15 58
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Equivalent Integrals
Alternative Lagrangian that gives the same equation of Motion doesn’t have
necessarily to differ by a total time derivative. For example
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj tdtqtqtLCI
( ) ( ) ( ) ( )[ ]2
2
2
1
2
2
2
1
2121
2
1
qqqqL
qqqqL
b
a
−−+=
−=
0&0
0&0
22
22
11
11
11
22
22
11
=+=
∂
∂
−
∂
∂
=+=
∂
∂
−
∂
∂
=+=
∂
∂
−
∂
∂
=+=
∂
∂
−
∂
∂
qq
q
L
q
L
td
d
qq
q
L
q
L
td
d
qq
q
L
q
L
td
d
qq
q
L
q
L
td
d
bbbb
aaaa
( ) ( )[ ]2
21
2
21
2
1
qqqqLL ab −−−=−
Return to Table of Content
59. A Geodesic Field is defined as a Field of Contravariant Vectors , given
at each point of a finite Region G in the n+1 Space (t, q1
, q2
,…,qn
) by a set of n class C2
functions ψj
(t,qk
) that are such that, for a suitably chosen function S = S (t,qk
), the
following conditions are satisfied
while
One other condition (Jacobi) that the curves that define a Geodesic Field,
is that they don’t intersect for t1 < t < t2.
( )kjj
qtq ,ψ=
( ) ( ) ( )kjjkkkk
qtqwhenever
td
Sd
qqtLqqtL ,0,,:,,*
ψ==−=
( ) otherwiseqqtL kk
0,,*
>
( )kjj
qtq ,ψ=
04/08/15 59
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Hamilton-Jacobi Theory
Geodesic Field
See “Calculus of Variation” for a detailed exposition.
Note: Since we see that it is equivalent to “Action”.( ) ( )∫=
t
t
kk
tdqqtLtS
1
,,
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj tdtqtqtLCI
60. 04/08/15 60
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Hamilton-Jacobi Theory
Geodesic Field (continue – 1)
For any other curve K in G that joins the points P1 and P2 we have
( ) ( ) FieldGeodesictqqtdqqtL jj
t
t
kk
⊂=Γ=∫ :0,,
2
1
0
*
( ) ( ) FieldGeodesictqqKtdqqtL jj
t
t
kk
⊄=>∫
>
:0,,
2
1
0
*
Therefore the Integral I* (Γ) is a local minimum, and since this is an Equivalent
Integral to I (Γ), this is also a local minimum in G.
( )kjj
qtq ,ψ= is a System of n First-Order Differential Equations, that may be
integrated to cover the region G. Let Γ: qj
= qj
(t) be a member of this family and
Let P1 and P2 the points on Γ, corresponding to t1 and t2, It follows that
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj tdtqtqtLCI
61. 04/08/15 61
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Hamilton-Jacobi Theory
Basic Properties of Geodesic Field
Since ( ) ( ) ( ) FieldGeodesictqqq
q
S
t
S
qqtLqqtL jjl
l
kkkk
⊂=Γ=
∂
∂
−
∂
∂
−= :0,,:,,*
( ) ( ) ( )kjj
jj
p
q
L
jj
kk
j
kk
qtqwhenever
q
S
p
qd
S
q
qqtL
q
qqtL
jj
,
,,,,
0
*
ψ=
∂
∂
−=
∂
−
∂
∂
=
∂
∂
=
=
∂
∂
Therefore ( ) FieldGeodesictqq
q
S
p jj
jj ⊂=Γ
∂
∂
= :
( ) ( )kj
k
kjj
qtpqtq ,,, ψφ ==
This defines the Covariant Vector Field pj = pj (t, qk
) as a function of position in
G. Assuming the one-to-one correspondence between pj and (j,k=1,2,…,n), we
have
k
q
We get ( ) l
l
q
S
p
q
l
l
kk
p
t
S
q
q
S
t
S
qqtL
ll
ll
φ
φ
+
∂
∂
=
∂
∂
+
∂
∂
=
∂
∂
=
=
,, ( ) ( )
( )
∂
∂
=+−=
=
∂
∂
=
k
k
pqtq
q
S
p
l
l
kkkk
q
S
qtHpqqtLqqtH
k
kkk
kk
,,,,,,
,,φ
φ
0,, =
∂
∂
+
∂
∂
k
k
q
S
qtH
t
S
and
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj tdtqtqtLCI
62. 04/08/15 62
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Hamilton-Jacobi Theory
William Rowan
Hamilton
1805-1865
Carl Gustav Jacob
Jacobi
(1804-1851)
0,, =
∂
∂
+
∂
∂
k
k
q
S
qtH
t
S
Hamilton-Jacobi Equation
Hamilton-Jacobi is a First-Order Nonlinear Partial
Differential Equation for the Scalar Function
S = S (t,qk
), that defines the Geodesic Field through
from which a Unique Vector Field
is obtained
jj
q
S
p
∂
∂
=
( ) ( )kj
k
kjj
qtpqtq ,,, ψφ ==
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj tdtqtqtLCI
63. 04/08/15 63
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Hamilton-Jacobi Theory
William Rowan
Hamilton
1805-1865
Carl Gustav Jacob
Jacobi
(1804-1851)
0,, =
∂
∂
+
∂
∂
k
k
q
S
qtH
t
S
Start with jj
q
S
p
∂
∂
=
( ) l
ljjj
k
j
q
qq
S
xt
S
q
qtS
td
d
td
pd
∂∂
∂
+
∂∂
∂
=
∂
∂
=
22
,
Partially Differentiate the Hamilton Jacobi Equation
with respect to qj
( ) ( ) 0
,,,, 222
=
∂∂
∂
+
∂
∂
+
∂∂
∂
=
∂
∂
∂
∂
+
∂
∂
+
∂∂
∂ ∂
∂
=
=
∂
∂
l
ljjj
q
S
p
x
p
Hj
l
l
k
k
j
k
k
j
q
qq
S
q
H
tq
S
q
p
p
pqtH
q
pqtH
tq
S
ll
l
l
we obtain
j
j
q
H
td
pd
∂
∂
−=
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj tdtqtqtLCI
64. 04/08/15 64
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Hamilton-Jacobi Theory
William Rowan
Hamilton
1805-1865
Carl Gustav Jacob
Jacobi
(1804-1851)
we obtain
=
∂
∂
−=
=
∂
∂
=
nj
q
H
td
pd
nj
p
H
td
qd
j
j
j
j
,,2,1
,,2,1
( ) 0=
∂
∂
+=
∂
∂
−
∂
∂
=
=
∂
∂
∂
∂
=
∂
∂ j
j
td
pd
q
L
q
H
q
Ljjj
q
H
td
pd
q
L
q
L
td
d
LE
j
j
jj
A System of 2n First-Order Ordinary
Differential Equations which the curve
Γ must satisfy.
This is equivalent to Euler-Lagrange
n Second-Order Partial Differential
Equations, since
( )
k
jj
k
q
qqtL
p
∂
∂
=
,,
: Canonical Momentum
( ) ( )[ ] ( )k
kj
ji
ikk
k
k
pqtppqtqtLpqtH ,,,,,,:,, φφ +−= Hamiltonian
Hamilton’s
Equations
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj tdtqtqtLCI
65. 04/08/15 65
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Hamilton-Jacobi Theory
William Rowan
Hamilton
1805-1865
Carl Gustav Jacob
Jacobi
(1804-1851)
Let return to the condition
( ) ( ) ( ) ( ) 0
,,
,,,,*
≥
∂
∂
−
∂
∂
−= k
k
jj
jjjj
q
q
qtS
t
qtS
qqtLqqtL
where the equality holds for ( ) ( )kj
k
kjj
qtpqtq ,,, ψφ ==
We want to eliminate S from this inequality.
For this use
( ) ( )[ ] ( )l
lk
kl
ljj
p
q
S
j
j
j
pqtppqtqtL
q
S
qtH
t
qtS
jj
,,,,,,:,,
,
φφ +−=
∂
∂
=
∂
∂
−
=
∂
∂
( ) ( )[ ] ( ) ( ) 0
,
,,,,,,,, ≥
∂
∂
−+− k
k
j
l
lk
kl
ljjjj
q
q
qtS
pqtppqtqtLqqtL φφ
( )jjj
j qqtE ,,, φ : Weierstrass Excess Function
Weierstrass
Sufficiency
Condition for
a Local
Minimum
( ) ( ) ( ) ( ) 0,,,,:,,, ≥−
∂
∂
+−= kk
k
jjjjjjj
j q
q
L
qtLqqtLqqtE φφφ
and
( ) ( )
k
j
k
jj
k
q
qtS
q
qqtL
p
∂
∂
=
∂
∂
=
,,,
:
Karl Theodor Wilhelm
Weierstrass
(1815-1897)
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj tdtqtqtLCI
Return to Table of Content
66. 04/08/15 66
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Hamilton-Jacobi Theory
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj
tdtxtxtLCI
Example: Recovering Newton Equation
VF −∇= - Force on Mass m, due to External Potential V
rrmT
⋅=
2
1 - Kinetic Energy of Mass m
( )rV
- Potential Energy of the External Force
rm
r
L
p
=
∂
∂
= - Canonical Momentum
- HamiltonianEVTVrrmrrmVrrmxpLH =+=+⋅=⋅++⋅−=+−= :
2
1
2
1
:
VrrmVTL −⋅=−=
2
1
: - Lagrangian
67. 04/08/15 67
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Hamilton-Jacobi Theory
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj
tdtxtxtLCI
Example: Recovering Newton Equation (continue – 1)
S
r
S
rm
r
L
p ∇=
∂
∂
==
∂
∂
=
- Canonical Momentum
- HamiltonianVTVrrmH +=+⋅=
2
1
Hamilton-Jacobi Equation
where S is given by
VSS
m
VrrmH +∇⋅∇=+⋅=
2
1
2
1
0
2
1
=+∇⋅∇+
∂
∂
VSS
mt
S
Hamilton-Jacobi Equation
( ) 0,, =∇+
∂
∂
SrtH
t
S
68. 04/08/15 68
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Hamilton-Jacobi Theory
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj
tdtxtxtLCI
Example: Recovering Newton Equation (continue – 2)
0
2
1
=+∇⋅∇+
∂
∂
VSS
mt
S
Hamilton-Jacobi Equation
Let take the Gradient of this equation
( ) ( ) Vrr
r
m
p
t
VSS
mt
S rmpS
∇+⋅
∂
∂
+
∂
∂
=∇+∇⋅∇∇+
∂
∂
∇=
==∇
0
22
1
0
FVp
t
p
td
d
=−∇=
∂
∂
= Newton Equation
( ) p
t
rm
r
rp
t
p
td
d
∂
∂
=
∂
∂
⋅+
∂
∂
=
0
69. 04/08/15 69
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Hamilton-Jacobi Theory
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj
tdtxtxtLCI
Example: Classical Harmonic Oscillator In Equilibrium
Displaced from
Equilibrium
xmxkF =−= - Force of Spring on Mass m
2
2
1
xmT = - Kinetic Energy of Mass m
2
2
1
xkV = - Potential Energy of the Spring
xm
x
L
p
=
∂
∂
= - Canonical Momentum
- HamiltonianEVTxkxmxxmxkxmxpLH =+=+=⋅++−=+−= :
2
1
2
1
2
1
2
1
: 2222
22
2
1
2
1
: xkxmVTL −=−= - Lagrangian
02
2
>=
∂
∂
m
x
L
70. 04/08/15 70
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Hamilton-Jacobi Theory
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj
tdtxtxtLCI
Example: Classical Harmonic Oscillator (continue – 1)
In Equilibrium
Displaced from
Equilibrium- Hamiltonian( ) 2
2
2
1
2
1
:, xk
m
p
pxH +=
x
m
k
td
pd
mtd
xd
m
p
p
H
td
xd
xk
x
H
td
pd
−==⇒
=
∂
∂
=
−=
∂
∂
−=
1
2
2
Initial Conditions:
( )
( )
==
==
00
0
t
td
xd
Atx
( )
( ) ( ) m
k
tAmtxmtp
tAtx
=
−==
=
:
sin
cos
ω
ωω
ω
: Solution
On the minimizing curve Γ
( ) .
2
1
cos
2
1
sin
1
2
1
2
1
2
1
:, 2222222
2
constAktAkt
m
k
Am
m
xk
m
p
pxH ==+
=+= ωω
Hamilton’s Equations:
71. 04/08/15 71
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Hamilton-Jacobi Theory
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj
tdtxtxtLCI
Example: Classical Harmonic Oscillator (continue – 2)
In Equilibrium
Displaced from
Equilibrium
( ) ( )
td
Sd
tAktAktA
m
k
m
m
xk
m
p
VTpxL =−=−
=−=−= ωωω 2cos
2
1
cos
2
1
sin
1
2
1
2
1
2
1
, 22
2
2
2
( )
t
t
tA
k
ttA
k
tA
k
S
ω
ω
ω
ω
ωω
ω
ω
ω cos
sin
cos
2
1
cossin
2
1
2sin
4
1 222
−=−=−=
( )
t
t
x
k
xtS
ω
ω
ω cos
sin
2
1
, 2
−=
( ) HAk
t
xk
t
xtS tAx
−=−=−=
∂
∂ =
2
cos
2
2
2
1
cos
1
2
1, ω
ω
( ) ptA
k
t
t
x
k
x
xtS tAmp
m
k
tAx ωω
ω
ω
ω
ω
ωω
ω
ω
sincos
sin
cos
sin, −=
=
=
=−=−=
∂
∂
ω
ω
m
m
k
mkm
mk
kk
====
/
Return to Table of Content
72. 04/08/15 72
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj tdtqtqtLCI
Invariance Properties of the Fundamental Integral
Theorem of Noether for Single Integral
Amalie Emmy
Noether
(1882 –1935)
Consider the Functional ( ) ( ) ( )( )∫=
2
1
,,
t
t
jj tdtqtqtLCI
Symmetry of Lagrangian is a Geometric Property in which
quantities remain unchanged under coordinate transformation.
Invariance is an Algebraic or Analytic Property in which
“Integrals of Motion” are constant along System Trajectories..
Consider also a continuous family of coordinate transformation
qj (t) → qj (t,ε) parameterized by a single quantity ε.
We assume that the Lagrangian is invariant to this parameter
which implies a Symmetry of the System. Thus
( ) ( )( ) ( ) ( )( )0,,0,,,,,, === εεεε tqtqtLtqtqtL jjjj
( ) ( )( ) nj
q
q
Lq
q
Lq
q
Lq
q
L
tqtqtL
d
d j
j
j
j
n
j
j
j
j
j
jj ,,100,,,, 1
==
∂
∂
∂
∂
+
∂
∂
∂
∂
⇒=
∂
∂
∂
∂
+
∂
∂
∂
∂
= ∑ =
αααα
εε
α
73. 73
SOLO Classical Field Theories
Introduction to Lagrangian and Hamiltonian Formulation
Extremal of the Functional .( ) ( ) ( )( )∫=
2
1
,,
t
t
jj tdtqtqtLCI
Invariance Properties of the Fundamental Integral
Theorem of Noether for Single Integral (continue – 1)
Amalie Emmy
Noether
(1882 –1935)
nj
q
q
Lq
q
L j
j
j
j
,,10
==
∂
∂
∂
∂
+
∂
∂
∂
∂
αα
Since qi(ε) is a solution of Euler-Lagrange’s Equation we have
nj
q
L
q
L
td
d
jj
,,10
==
∂
∂
−
∂
∂
Substitute this in previous equation we obtain
( ) ( ) ( )
nj
tq
q
L
td
dtq
q
Ltq
q
L
td
d j
j
j
j
j
j
,,10
,,,
==
∂
∂
∂
∂
=
∂
∂
∂
∂
+
∂
∂
∂
∂
α
α
α
α
α
α
The quantity is a Constant of Motion.
( ) ( )
α
α
α
α
∂
∂
=
∂
∂
∂
∂ ,, tq
p
tq
q
L j
j
j
j
Noether Theorem is not of great importance in Particle Dynamics.
It becomes extremely important in Field Theory and in Quantum Mechanics.
nj
q
L
p
j
j ,,1 =
∂
∂
=
Return to Table of Content
74. 74
SOLO Foundation of Geometrical Optics
Fermat’s Principle (1657) in Optics
The Principle of Fermat (principle of the shortest optical path) asserts that the optical
length
of an actual ray between any two points is shorter than the optical ray of any other
curve that joints these two points and which is in a certain neighborhood of it.
An other formulation of the Fermat’s Principle requires only Stationarity (instead of
minimal length).
∫
2
1
P
P
dsn
An other form of the Fermat’s Principle is:
Principle of Least Time
The path following by a ray in going from one point in
space to another is the path that makes the time of transit of
the associated wave stationary (usually a minimum).
The idea that the light travels in the shortest path was first put
forward by Hero of Alexandria in his work “Catoptrics”,
cc 100B.C.-150 A.C. Hero showed by a geometrical method
that the actual path taken by a ray of light reflected from plane
mirror is shorter than any other reflected path that might be
drawn between the source and point of observation.
75. 75
SOLO Foundation of Geometrical Optics
Proof of Fermat’s Principle Using Calculus of Variations
We have:
constS =
constdSS =+
sˆ
∫
2
1
P
P
dsn
1
P
2
P
( ) ( ) ( )∫∫∫∫ =
+
+===
2
1
2
1
2
1
,,,,
1
1,,
1
,,
1
0
22
00
P
P
P
P
P
P
xdzyzyxF
c
xd
xd
zd
xd
yd
zyxn
c
dszyxn
c
tdJ
Let find the stationarity conditions of the Optical Path using the Calculus of Variations
( ) ( ) ( ) xd
xd
zd
xd
yd
zdydxdds
22
222
1
+
+=++=
Define:
xd
zd
z
xd
yd
y == &:
( ) ( ) ( ) 22
22
1,,1,,,,,, zyzyxn
xd
zd
xd
yd
zyxnzyzyxF ++=
+
+=
76. 76
SOLO Foundation of Geometrical Optics
Proof of Fermat’s Principle Using Calculus of Variations (continue – 1)
Necessary Conditions for Stationarity (Euler-Lagrange Equations)
( ) ( ) ( ) 22
22
1,,1,,,,,, zyzyxn
xd
zd
xd
yd
zyxnzyzyxF ++=
+
+=
0=
∂
∂
−
∂
∂
y
F
y
F
dx
d
( )
[ ] 2/122
1
,,
zy
yzyxn
y
F
++
=
∂
∂ [ ] ( )
y
zyxn
zy
y
F
∂
∂
++=
∂
∂ ,,
1 2/122
( )
[ ]
[ ] 01
1
,, 2/122
2/122
=
∂
∂
++−
++ y
n
zy
zy
yzyxn
xd
d
0=
∂
∂
−
∂
∂
z
F
z
F
dx
d
[ ] [ ]
0
11
2/1222/122
=
∂
∂
−
++++ y
n
zy
yn
xdzy
d
77. 77
SOLO Foundation of Geometrical Optics
Proof of Fermat’s Principle Using Calculus of Variations (continue – 2)
Necessary Conditions for Stationarity (continue - 1)
We have
[ ]
0
1
2/122
=
∂
∂
−
++ y
n
zy
yn
sd
d
y
n
sd
yd
n
sd
d
∂
∂
=
In the same way
[ ]
0
1
2/122
=
∂
∂
−
++ z
n
zy
zn
sd
d
z
n
sd
zd
n
sd
d
∂
∂
=
78. 78
SOLO Foundation of Geometrical Optics
Proof of Fermat’s Principle Using Calculus of Variations (continue – 3)
Necessary Conditions for Stationarity (continue - 2)
Using ( ) ( ) ( ) xd
xd
zd
xd
yd
zdydxdds
22
222
1
+
+=++=
we obtain 1
222
=
+
+
sd
zd
sd
yd
sd
xd
Differentiate this equation with respect to s and multiply by n
sd
d
0=
+
+
sd
zd
sd
d
n
sd
zd
sd
yd
sd
d
n
sd
yd
sd
xd
sd
d
n
sd
xd
sd
nd
sd
zd
sd
nd
sd
yd
sd
nd
sd
xd
sd
nd
=
+
+
222
sd
nd
and
sd
nd
sd
zd
n
sd
d
sd
zd
sd
yd
n
sd
d
sd
yd
sd
xd
n
sd
d
sd
xd
=
+
+
add those two equations
79. 79
SOLO Foundation of Geometrical Optics
Proof of Fermat’s Principle Using Calculus of Variations (continue – 4)
Necessary Conditions for Stationarity (continue - 3)
sd
nd
sd
zd
n
sd
d
sd
zd
sd
yd
n
sd
d
sd
yd
sd
xd
n
sd
d
sd
xd
=
+
+
Multiply this by and use the fact that to obtain
xd
sd
cd
ad
cd
bd
bd
ad
=
xd
nd
sd
zd
n
sd
d
xd
zd
sd
yd
n
sd
d
xd
yd
sd
xd
n
sd
d
=
+
+
Substitute and in this equation to obtain
y
n
sd
yd
n
sd
d
∂
∂
=
z
n
sd
zd
n
sd
d
∂
∂
=
xd
zd
z
n
xd
yd
y
n
xd
nd
sd
xd
n
sd
d
∂
∂
−
∂
∂
−=
Since n is a function of x, y, z
x
n
xd
zd
z
n
xd
yd
y
n
xd
nd
zd
z
n
yd
y
n
xd
x
n
nd
∂
∂
=
∂
∂
−
∂
∂
−→
∂
∂
+
∂
∂
+
∂
∂
=
and the previous equation becomes
x
n
sd
xd
n
sd
d
∂
∂
=
80. 80
SOLO Foundation of Geometrical Optics
Proof of Fermat’s Principle Using Calculus of Variations (continue – 5)
Necessary Conditions for Stationarity (continue - 4)
We obtained the Euler-Lagrange Equations:
x
n
sd
xd
n
sd
d
∂
∂
=
y
n
sd
yd
n
sd
d
∂
∂
=
z
n
sd
zd
n
sd
d
∂
∂
=
k
sd
zd
j
sd
yd
i
sd
xd
sd
rd
kzjyixr
ˆˆˆ
ˆˆˆ
++=
++=
Define the unit vectors in the x, y, z directionskji ˆ,ˆ,ˆ
The Euler-Lagrange Equations can be written as:
n
sd
rd
n
sd
d
∇=
The equation is called Eikonal Equation
Eikonal (from Greek έίκων = eikon → image) .
See “Geometrical Optics” Presentation
81. 81
SOLO Foundation of Geometrical Optics
Proof of Fermat’s Principle Using Calculus of Variations (continue – 6)
Hamilton’s Canonical Equations
Define ( )
[ ]
( )
( )
[ ]
( )
sd
zd
zyxn
zy
zzyxn
z
F
p
sd
yd
zyxn
zy
yzyxn
y
F
p
z
y
,,
1
,,
:
,,
1
,,
:
2/122
2/122
=
++
=
∂
∂
=
=
++
=
∂
∂
=
( )( ) ( )2222222
1 zynzypp zy +=+++
Adding the square of twose two equations gives
( )
( )
2
222
2
22
1
=
+−
=++
xd
sd
ppn
n
zy
zy
from which
Substituting in ( ) ( ) ( ) 22
22
1,,1,,,,,, zyzyxn
xd
zd
xd
yd
zyxnzyzyxF ++=
+
+=
gives
( )
( )222
2
,,,,
zy
zy
ppn
n
ppzyxF
+−
=
( ) ( ) ( ) 22
22
1,,1,,,,,, zyzyxn
xd
zd
xd
yd
zyxnzyzyxF ++=
+
+=
82. 82
SOLO Foundation of Geometrical Optics
Proof of Fermat’s Principle Using Calculus of Variations (continue – 7)
Hamilton’s Canonical Equations (continue – 1)
From ( )
[ ]
( )
( )
[ ]
( )
sd
zd
zyxn
zy
zzyxn
z
F
p
sd
yd
zyxn
zy
yzyxn
y
F
p
z
y
,,
1
,,
:
,,
1
,,
:
2/122
2/122
=
++
=
∂
∂
=
=
++
=
∂
∂
=
solve for
( )
( )222
2
,,,,
zy
zy
ppn
n
ppzyxF
+−
=and
( )
( )222
222
zy
z
zy
y
ppn
p
z
ppn
p
y
+−
=
+−
=
Define the Hamiltonian
( ) ( )
( ) ( ) ( )
( ) ( ) ( )
sd
xd
zyxnppzyxn
ppn
p
ppn
p
ppn
n
zpypppzyxFppzyxH
zy
zy
z
zy
y
zy
zyzyzy
,,,,
,,,,:,,,,
222
222
2
222
2
222
2
−=+−−=
+−
+
+−
+
+−
−=
++−=
83. 83
SOLO Foundation of Geometrical Optics
Proof of Fermat’s Principle Using Calculus of Variations (continue – 8)
Hamilton’s Canonical Equations (continue – 2)
From
We obtain the Hamilton’s Canonical Equations
( ) ( ) ( ) ( )
sd
xd
zyxnppzyxnppzyxH zyzy ,,,,,,,,
222
−=+−−=
( )
( )222
222
zy
z
z
zy
y
y
ppn
p
p
H
xd
zd
z
ppn
p
p
H
xd
yd
y
+−
=
∂
∂
==
+−
=
∂
∂
==
( )
( )222
222
zy
z
zy
y
ppn
z
n
n
z
H
xd
pd
ppn
y
n
n
y
H
xd
pd
+−
∂
∂
−=
∂
∂
−=
+−
∂
∂
−=
∂
∂
−=
84. 84
SOLO Foundation of Geometrical Optics
Proof of Fermat’s Principle Using Calculus of Variations (continue – 9)
Hamilton’s Canonical Equations (continue – 3)
From
( ) ( ) ( ) ( )
sd
xd
zyxnppzyxnppzyxH zyzy ,,,,,,,,
222
−=+−−=
( )222
zy ppn
n
sd
xd
+−
=
By similarity with ( )
sd
yd
zyxnpy ,,=
define ( ) ( ) ( ) ( )222
,,,,,,,,: zyzyx ppzyxnppzyxH
sd
xd
zyxnp +−=−==
Let differentiate px with respect to x
( ) x
H
xd
Hd
ppn
x
n
n
xd
pd
zy
x
∂
∂
−=−=
+−
∂
∂
=
222
Let compute
( )
( )
x
n
n
ppn
ppn
x
n
n
sd
xd
xd
pd
sd
pd zy
zy
xx
∂
∂
=
+−
+−
∂
∂
==
222
222
85. 85
SOLO Foundation of Geometrical Optics
Proof of Fermat’s Principle Using Calculus of Variations (continue – 10)
Hamilton’s Canonical Equations (continue – 4)
and
( )
( )
x
n
n
ppn
ppn
x
n
n
sd
xd
xd
pd
sd
pd zy
zy
xx
∂
∂
=
+−
+−
∂
∂
==
222
222
( )
( )
y
n
n
ppn
ppn
y
n
n
sd
xd
xd
pd
sd
pd zy
zy
yy
∂
∂
=
+−
+−
∂
∂
==
222
222
( )
( )
z
n
n
ppn
ppn
z
n
n
sd
xd
xd
pd
sd
pd zy
zy
zz
∂
∂
=
+−
+−
∂
∂
==
222
222
n
sd
pd
∇=
xp
nsd
xd 1
=
( )
( )
y
zy
zy
y
p
nn
ppn
ppn
p
sd
xd
xd
yd
sd
yd 1
222
222
=
+−
+−
==
( )
( )
z
zy
zy
z
p
nn
ppn
ppn
p
sd
xd
xd
zd
sd
zd 1
222
222
=
+−
+−
==
p
nsd
rd ray
1
=
We recover the result from Geometrical Optics Return to Table of Content
86. 04/08/15 86
SOLO Classical Field Theories
The Inverse Square Law of Forces
The Two Body Central Force Problem
Assume a system of two mass points m1 and m2 located at
, respectively, subject to an interaction potential V,
where V is any function of the range vector between particles.
21 randr
Define:
( ) ( )212211
12
/
:
mmrmrmR
rrr
c ++=
−=
- range vector between particles
- system center of mass
21
1
2
21
2
1 ,
mm
rm
Rr
mm
rm
Rr cc
+
+=
+
−=
We obtain:
The kinetic energy of the system:
+
+⋅
+
++
+
−⋅
+
−=⋅+⋅=
21
1
21
1
2
21
2
21
2
1222111
2
1
2
1
2
1
2
1
mm
rm
R
mm
rm
Rm
mm
rm
R
mm
rm
RmrrmrrmT cccc
( ) rr
mm
mm
RRmmT
M
cc
⋅
+
+⋅+=
21
21
21
2
1
2
1or
( ) ( )
,,
2
1
2
1
21 rrVrrMRRmmVTL cc −⋅+⋅+=−=
The Lagrangian of the system is
87. 04/08/15 87
SOLO Classical Field Theories
The Inverse Square Law of Forces
( ) ( ) ( )
( )2121
222
/:
2
1
2
1
mmmmM
rVrrMrVrrMVTL
+=
−+=−⋅=−= θ
When V is a function of r only like in classical gravitation and
electromagnetic fields, we can write, in polar coordinates and
ignoring the term describing the motion of center of mass
The Lagrange’s Equations are
,2,10 =∀=
∂
∂
−
∂
∂
∂
∂
i
q
L
t
q
L
td
d
ii
2. r - independent variable
r
V
rM
r
L
rM
r
L
∂
∂
−=
∂
∂
=
∂
∂ 2
, θ
1. θ - independent variable
0,2
=
∂
∂
=
∂
∂
θ
θ
θ
L
rM
L
( ) ( ) 02
==
∂
∂
−
∂
∂
θ
θθ
rM
td
dLL
td
d
( )
02
=
∂
∂
+−=
∂
∂
−
∂
∂
r
V
rMrM
r
L
r
L
td
d
θ
88. 04/08/15 88
SOLO Classical Field Theories
The Inverse Square Law of Forces
The Specific Angular Momentum and Angular Momentum are
defined as
θθ 22
:&: rMhMlrh ===
( ) ( ) 02
==
∂
∂
−
∂
∂
θ
θθ
rM
td
dLL
td
d
The Equation means that Angular
Momentum is constant (Conservation of Angular Momentum )
This Equation can be rewritten as
θdrMdtl 2
=
that implies
=⇒=
θθθ d
d
rM
l
d
d
rM
l
dt
d
d
d
rM
l
dt
d
222
2
2
a
b
The Area swept out by one of the body when moving around
the other (see Figure) is given by
( )θdrrAd
2
1
=
It follows that
.
22
const
h
d
Ad
rM
l
td
Ad
===
θ
This is Kepler Second Law.
89. 04/08/15 89
SOLO Classical Field Theories
The Inverse Square Law of Forces
02
=
∂
∂
+−
r
V
rMrM θReturn to the equation
θ2
: rMl =and
We have ( ) ( ) 0
22 2
2
2
2
3
2
=
++=
+
∂
∂
+=
∂
∂
+− rV
rM
l
rd
d
rMrV
rM
l
r
rM
r
V
rM
l
rM
or ( ) ( )
( ) ( ) 2
2
2
2
2
:
2
r
l
rVrV
rV
rd
d
rV
rM
l
rd
d
rM
eff
eff
µ
+=
−=
+−=
Multiplying the differential equation by we obtainr
( ) ( )rV
td
d
rV
rd
d
td
rd
rM
td
d
rrM effeff −=−=
= 2
2
1
or 0
2
1 2
==
+
energy
total
energy
potential
eff
energy
kinetic
E
td
d
VrM
td
d
The total Energy is conservedeffVrME += 2
2
1
:
90. 04/08/15 90
SOLO Classical Field Theories
The Inverse Square Law of Forces
The total Energy is conservedeffVrME += 2
2
1
:
Solving for we obtainr
( )
−−±=−±= 2
2
2
22
rM
l
VE
M
VE
M
r eff
or
−−
=
2
2
2
2
rM
l
VE
M
rd
td
Using we obtain
θd
d
rM
l
dt
d
2
= 2
222
122
1
r
rd
rl
VM
l
EM
d
−−
=θ
Consider the case where V (r) = -k/r = - k u
ud
uu
l
kM
l
EM
d
2
22
22
1
−−
−
=θ
Integrating this expression gives
1
2
1
1
sin
28
2
2
sin
2
2
2
1
2
22
2
1
+
−
=
+
+−
=− −−
kM
lE
rkM
l
l
kM
l
EM
l
kM
u
iθθ
91. 04/08/15 91
SOLO Classical Field Theories
The Inverse Square Law of Forces
1
2
1
1
sin
28
2
2
sin
2
2
2
1
2
22
2
1
+
−
=
+
+−
=− −−
kM
lE
rkM
l
l
kM
l
EM
l
kM
u
iθθ
Inverting this expression we obtain
( )
−+−= i
kM
lE
l
kM
r
θθsin
2
11
1
2
2
2
This is usually written as
( ){ }
2
2
2
2
1:
sin1
1
kM
lE
e
e
l
kM
r
i
+=
−−= θθ
This is a equation of Conic Section:
1.If e > 1 and E > 0, the trajectory is a Hyperbola.
2. If e = 1 and E = 0, the trajectory is a Parabola.
3. If e < 1 and E < 0, the trajectory is a Ellipse.
4. If e = 0 and E = -mk2
/(2l2
), the trajectory is a Circle.
Return to Table of Content
92. 04/08/15 92
SOLO
Four-Dimensional Formulation of the Theory of Relativity
Special Relativity Theory
We introduce a 4-dimensional space-time or four-vector x with components:
( ) ( ) ctxxxxxxxx == 003210
,,,,:
µ
The differential length element is defined as:
( ) ( ) ( ) ( ) ( ) ( ) 220232221202
: xdxdxdxdxdxds
−=−−−=
or
( ) νµ
µν
µ ν
νµ
µν dxdxgdxdxgds
summationsEimstein
convention
'3
0
3
0
2
== ∑∑= =
The metric corresponding to this differential length is given by g:
( )µνgg =
−
−
−
=
1000
0100
0010
0001
therefore: ( )νµµν
≠=−==== 0,1,1 33221100 ggggg
We can see that Igg =
=
−
−
−
−
−
−
=
1000
0100
0010
0001
1000
0100
0010
0001
1000
0100
0010
0001
93. 04/08/15 93
SOLO
Four-Dimensional Formulation of the Theory of Relativity (continue – 1)
Therefore since we have
γ
µ
νγ
µν δ=gg µν
µν
gg =
If a 4-vector has the contravariant components A0
,A1
,A2
,A3
we have
( ) ( ) ( )32103210
,,,,,, AAAAwhereAAAAAAA ===
α
Using the g metric we get the same 4-vector described by the covariant components:
( )AA
A
A
A
A
A
A
A
A
AgA
−=
−
−
−
=
−
−
−
== ,
1000
0100
0010
0001
0
3
2
1
0
3
2
1
0
β
αβα
The Scalar Product of two 4-vectors is:
( )( ) ( )( ) αα
αβαβ
αβα
αα
α ABgABgABABAABBABAABBAB ==⋅−=−==−=
000000
,,,,
Special Relativity Theory
94. 04/08/15 94
SOLO
Four-Dimensional Formulation of the Theory of Relativity (continue – 1)
Therefore since we have
γ
µ
νγ
µν δ=gg µν
µν
gg =
If a 4-vector has the contravariant components A0
,A1
,A2
,A3
we have
( ) ( ) ( )32103210
,,,,,, AAAAwhereAAAAAAA ===
α
Using the g metric we get the same 4-vector described by the covariant components:
( )AA
A
A
A
A
A
A
A
A
AgA
−=
−
−
−
=
−
−
−
== ,
1000
0100
0010
0001
0
3
2
1
0
3
2
1
0
β
αβα
The Scalar Product of two 4-vectors is:
( )( ) ( )( ) αα
αβαβ
αβα
αα
α ABgABgABABAABBABAABBAB ==⋅−=−==−=
000000
,,,,
Special Relativity Theory
95. 95
SOLO
Special Relativity Theory
Four-Dimensional Formulation of the Theory of Relativity (continue – 2)
Let introduce the following definitions:
∇
∂
∂
=
∂
∂
∂
∂
∂
∂
∂
∂
=
∂
∂
=∂
−∇
∂
∂
=
∂
∂
−
∂
∂
−
∂
∂
−
∂
∂
=
∂
∂
=∂
,,,,:
,,,,:
03210
03210
xxxxxx
xxxxxx
αα
α
α
The 4-divergence of a 4-vector A is the invariant:
( ) ( ) A
x
A
AA
x
AAA
x
A
⋅∇+
∂
∂
=
∇
∂
∂
=∂=−
−∇
∂
∂
=∂ 0
0
0
0
0
0
,,,, α
αα
α
The four-dimensional Laplacian operator (d’Alembertian) is defined as:
∇−
∂
∂
=
∇
∂
∂
−∇
∂
∂
=∂∂=
−∇
∂
∂
∇
∂
∂
=∂∂= 2
20
2
0000
,,,,:
xxxxx
α
αα
α
96. 04/08/15 96
SOLO
Four-Dimensional Formulation of the Theory of Relativity (continue – 3)
We have:
( ) ( ) ( ) ( ) ( )
−=−=−−−=
2
2
22222232221202 1
1
dt
xd
c
dtcxddtcdxdxdxdxds
We define
- the velocity vector of the particle in the inertial frame.
td
xd
u
=
2
1
1
:&:
u
uu
c
u
β
γβ
−
==
( ) ( ) 22222222
2
2
222
/11 τγβ dcdtcdtc
c
u
dtcds uu ==−=
−=
where
( ) ( )t
dt
dtd
u
u
γ
βτ =−=
2
1
is the differential of the proper time τ.
Special Relativity Theory
97. 04/08/15 97
SOLO
Four-Dimensional Formulation of the Theory of Relativity (continue – 4)
4-Coordinates Vector
The 4-coordinates vector is:
( ) ( ) ( ) ( )xxxxxxxxxxxxxx
−=−−−=== ,,,,&,,,, 0321003210
α
α
( )( ) ( ) ( ) 23210000 22222
,, sdxdxdxdxdxdxdxdxdxdxdxdxdxd =−−−=⋅−=−=
α
α
Special Relativity Theory
98. 04/08/15 98
SOLO
Four-Dimensional Formulation of the Theory of Relativity (continue – 5)
4-Velocity Vector
( ) ( ) td
xd
uUUuc
d
dt
dt
xd
d
dt
dt
dx
d
xd
d
dx
U uu
===
=
= ,,,,: 0
00
γγ
ττττ
α
( ) ( ) 20
0
u
1
1
:,,,:
−
=−=−=
−=
c
UUuc
d
xd
d
dx
U uuu γγγ
ττ
α
The 4-Velocity vector is defined as:
( ) ( ) ( ) 2
2
2
2
2
2
222
1
1
1
,, c
c
u
c
c
u
ucucucUU uuuuu =
−
−
=−=−=
∆
γγγγγα
α
( ) ( ) ( ) ( ) ( )
( ) ( )
( ) ( )
−=−
=
=−=
−+−
=
=−+−
===
ττττ
ττττττ
ττττ
α
α
d
Ud
d
dU
UUUU
d
Ud
d
dU
d
Ud
U
d
dU
U
d
Ud
d
dU
UUUU
d
Ud
d
dU
UU
d
d
UUUUUU
d
d
UU
d
d
d
dc
,,2,,2
22,,,,
,,,,0
0
00
0
0
0
0
00
0
0000
2
( ) ( ) ( ) ( ) 0==== α
αα
αα
αα
α
ττττ
UU
d
d
U
d
d
UU
d
d
UUU
d
d
Special Relativity Theory
99. 04/08/15 99
SOLO
Four-Dimensional Formulation of the Theory of Relativity (continue – 5)
4-Moment Vector
The 4-Momentum vector of the mass m is defined as: ( )UUmUmp
,000 == αα
2
02
2
0
000
0
1
1
:
−
==
==
−
===
c
u
m
mofEnergymcE
c
E
mc
c
u
cm
cmUmp uγ
pumu
c
u
m
umUm u
==
−
==
2
0
00
1
γ
Therefore:
( ) ( ) ( ) ( )UUmUmpppUUmUmppp
−==−==== ,,&,, 000
0
000
0
αα
αα
22
0
2
0
2
2
2
,, cmUUmp
c
E
p
c
E
p
c
E
pp ==
−=
−
= α
α
α
α
from which we get: ( ) ( )22
0
22222
cmcpcmE +==
Special Relativity Theory
100. 100
SOLO
Four-Dimensional Formulation of the Theory of Relativity (continue – 6)
4-Force Vector
The 4-Force vector on the mass m is defined as:
=
==
ττττ
µµ
d
pd
d
Ed
c
p
c
E
d
d
p
d
d
F
,
1
,:
From the relations:
( ) u
u
u
d
dtdt
dtd γ
τγ
βτ =→=−=
2
1
( ) ( )
c
uF
d
td
td
rd
c
F
d
Ed
c
EdcmEdrdFdT u
⋅
=⋅=→=−=⋅=
γ
ττ
12
0
F
td
pd
d
td
d
pd
u
γ
ττ
==
Special Relativity Theory
2
u
1
1
:
−
=
c
uγ
( )
( )
−⋅=
−
⋅
==
⋅=
⋅
==
F
c
u
FF
c
uF
d
pd
F
F
c
u
FF
c
uF
d
pd
F
uu
u
uu
u
,,:
,,:
γγ
γ
τ
γγ
γ
τ
µ
µ
µ
µ
101. 101
SOLO
Four-Dimensional Formulation of the Theory of Relativity (continue –7)
4-Force Vector (continue – 1)
Assuming that the rest mass doesn’t change :00
=
τd
dm
( ) τττ
µ
µµµ
d
dU
mUm
d
d
p
d
d
F 00 ===
Using the relation:
( ) ( ) ( ) ( ) 0==== α
αα
αα
αα
α
ττττ
UU
d
d
U
d
d
UU
d
d
UUU
d
d
we get:
00 ==
τ
µ
µ
µ
µ
d
dU
UmFU
Special Relativity Theory
102. 102
SOLO
Four-Dimensional Formulation of the Theory of Relativity (continue –8)
4-Force Vector (continue – 2)
Assuming that the rest mass changes ,:00
≠
τd
dm
( ) µµµ
µ
µµ
ττττ
Π+=+== FU
d
md
d
Ud
mUm
d
d
p
d
d 0
00
Using the relation: ( ) ( ) ( ) ( ) 0==== α
αα
αα
αα
α
ττττ
UU
d
d
U
d
d
UU
d
d
UUU
d
d
where:
00 ==
τ
µ
µ
µ
µ
d
dU
UmFU
Special Relativity Theory
µµ
µ
µ
ττ
U
d
md
d
Ud
mF 0
0 :,: =Π=
( )
( )
−
⋅
==
⋅
==
=
=
F
c
uF
d
pd
F
F
c
uF
d
pd
F
u
u
constm
u
u
constm
γ
γ
τ
γ
γ
τ
µ
µ
µ
µ
,:
,:
.
.
0
0
103. 103
SOLO
Four-Dimensional Formulation of the Theory of Relativity (continue –9)
4-Force Vector (continue – 3)
Assuming that the rest mass changes ,:00
≠
τd
dm
Special Relativity Theory
( ) ( ) dt
xd
uUUuc
d
dt
dt
xd
d
dt
dt
dx
d
xd
d
dx
U uu
===
=
= ,,,,: 0
00
γγ
ττττ
α
( ) ( ) ( )2
0
0
/1/1:,,,: cuUUuc
d
xd
d
dx
U uuu −=−=−=
−= γγγ
ττ
α
The 4-Velocity vector is defined as:
Let define:
Π−
Φ
=Π
Π
Φ
=Π uuuu
cc
γγγγ α
α
,:,,:
( ) ( ) 02
:,, Φ=Π⋅−Φ=
Π−
Φ
=Π
u
c
ucU uuuuu γγγγγα
α
µµµ
µ
µ
ττ
Π+=+ FU
d
md
d
Ud
mU 0
0 02 0
0
0
0
Φ
Π+=+ µ
µ
µ
µ
µ
µ
µ
µ
ττ
UFUUU
d
md
d
Ud
Um
c
τ
α
α
d
md
cU 020
=Π=Φ
The 4-Velocity Momentum
vector that the particle loses
per unit proper time τ.
104. 104
SOLO
Four-Dimensional Formulation of the Theory of Relativity (continue –10)
4-Force Vector (continue – 4)
Assuming that the rest mass changes ,:00
≠
τd
dm
Special Relativity Theory
µ
µ
µµµ
µ
ττ
D
R
U
d
md
F
d
Ud
m 0
0 −Π+=
µ
µ
τ
D
d
Ud
m =0
µµ
τ
µµµ
µµµ
τ
U
c
U
d
md
R
RFD
c
d
md
2
0
0
020
:
:
Φ
−Π=−Π=
+=
Φ=
Fμ
– External Force
Rμ
– Reaction Force
Dμ
– Driving Force
0
0
00
2
0
20
=+=
=
Φ
−Π=
Φ
µ
µ
µ
µ
µ
µ
µ
µ
µ
µ
µ
µ
RUFUDU
UU
c
URU
c
Π+Φ+⋅=Π+=
=
F
c
uF
c
Fp
c
E
d
d
p
d
d
u ,
11
, 0
γ
ττ
µµµ
( ) u
u
u
d
dtdt
dtd γ
τγ
βτ =→=−=
2
1
Also
Π+Φ+⋅=
=
F
c
uF
c
p
c
E
td
d
p
td
d
,
11
, 0µ
105. 105
SOLO
Four-Dimensional Formulation of the Theory of Relativity (continue –11)
4-Force Vector (continue – 5)
Assuming that the rest mass changes ,:00
≠
τd
dm
Special Relativity Theory
( ) ( ) ( )PcQdtcdt
dt
cdQ
u
uu
dtd u
δδ
γ
γγτδ
γτ
µµ
,/,/,/ 00
/
=ΠΦ=ΠΦ=Π=
=
In special cases the rate of change of Πμ
may be due to emission or absorption
of Heat by the particle
where
Π=
Φ=
tdP
tdQ
δ
δ 0
106. 04/08/15 106
SOLO
Four-Dimensional Formulation of the Theory of Relativity
Special Relativity Theory
Principle of Last Action for 4-Vector for a Free Particle (zero external forces)
We want to define the Action Integral for 4-Vectors, similar to Fermat Principle in
Optics, to recover the 4-Momentum and 4-Force Vectors. Define
∫∫ =−=
2
1
:
t
t
b
a
tdLsdαA α is a constant, to be defined
( )22
/1 cudtcsd −=Using we obtain ∫∫ =−−=
2
1
2
1
22
/1:
t
t
t
t
tdLtdcucαA
Therefore the Lagrangian is
c
u
ccucL
2
/1
2
22 α
αα +−≈−−=
Since the constant α c in the Lagrangian doesn’t affect the equations of motion,
we concentrate on the second term that must be equal to Energy. We choose α to
obtain the non-relativistic kinetic energy m0u2
/2 (m0 – rest mass), i.e.:
cm0=α
222
0 /1 cucmL −−= ∫∫ −−=−−=
2
1
2
1
0
222
0 /1:
s
s
t
t
sdcmtdcucmA
( ) ( ) uzyxqzyxq
=== ,,&,,
107. 04/08/15 107
SOLO
Four-Dimensional Formulation of the Theory of Relativity
Special Relativity Theory
Canonical Momentum
222
0 /1 cucmL −−=
( )( ) um
cu
um
czyxcm
z
y
x
q
L
p
=
−
=++−−
∂∂
∂∂
∂∂
=
∂
∂
=
22
022222
0
/1
/1
/
/
/
( )( ) 0/1
/
/
/
22222
0 =++−−
∂∂
∂∂
∂∂
=
∂
∂
czyxcm
z
y
x
q
L
Particle Equation of Motion
Q
td
pd
cu
um
td
d
q
L
q
L
td
d
==
−
=
∂
∂
−
∂
∂
22
0
/1
- are the External Forces acting on the particle (zero for free particle)Q
Principle of Last Action for 4-Vector for a Free Particle
22
0
/1
:
cu
m
m
−
= - relativistic mass of Particle at velocity u
Free Particle Lagrangian
108. 04/08/15 108
SOLO
Four-Dimensional Formulation of the Theory of Relativity
Special Relativity Theory
222
0 /1 cucmL −−=
Principle of Last Action for 4-Vector for a Free Particle
The Free Particle Hamiltonian is defined as: LpH −⋅= u:
( )( ) um
cu
um
czyxcm
z
y
x
q
L
p
=
−
=++−−
∂∂
∂∂
∂∂
=
∂
∂
=
22
022222
0
/1
/1
/
/
/
where:
therefore:
2
22
2
0222
022
0
/1
/1u
/1
u: cm
cu
cm
cucm
cu
um
LpH =
−
=−+⋅
−
=−⋅=
We van see that the Hamiltonian H derived from the Lagrangian L is equal to the Total
Energy E of the Free Particle
Ecm
cu
cm
LpH ==
−
=−⋅= 2
22
2
0
/1
u:
Free Particle Lagrangian
109. 04/08/15 109
SOLO
Four-Dimensional Formulation of the Theory of Relativity
Special Relativity Theory
α
αUUcucmcucmL 22
0
222
0 /1/1 −−=−−=
Principle of Last Action for 4-Vector for a Free Particle (Covariant Treatment)
Let use: UαUα
= c2
to write
∫∫∫ −=−=−−=
2
1
2
1
2
1
00
222
0 /1:
τ
τ
α
α
τ
τ
ττ dUUcmdccmtdcucm
t
t
A
We defined ( ) u
u
u
d
dtdt
dtd γ
τγ
βτ =→=−=
2
1 2
u
1
1
:
−
=
c
uγ
therefore the Action Integral is
To use this for a variational calculation we must add the constraint
2
cUU =α
α 0=
τ
α
α
d
Ud
Uor equivalently
This can be added using Lagrange’s multipliers technique, but here we use a
different approach.
ττ
ττ
τ βα
αβα
α
α
αα
α
β
αβα
dcxdxdgxdxdd
d
xd
d
xd
dUU
xdgxd
====
=
110. 04/08/15 110
SOLO
Four-Dimensional Formulation of the Theory of Relativity
Special Relativity Theory
Principle of Last Action for 4-Vector for a Free Particle (Covariant Treatment)
∫∫∫ −=−=−−=
2
1
2
1
2
1
00
222
0 /1:
τ
τ
α
α
τ
τ
ττ dUUcmdccmtdcucm
t
t
A
Action Integral is
where s = s (τ) is any monotonically increasing function of τ.
ττ βααβ
βα
αβα
α dcsd
sd
xd
sd
xd
gxdxdgdUU ===
∫−=
2
1
0:
s
s
sd
sd
xd
sd
xd
gcm βααβ
A
sd
xd
sd
xd
gcmL βααβ
0: −=
( ) ( )γδ
αβ
gg =
−
−
−
=
1000
0100
0010
0001
sd
xd
sd
xd
sd
xd
cm
sd
xd
sd
xd
g
sd
xd
g
sd
xd
g
cm
sd
xd
L
x
L
jj
β
β
α
βααβ
αββα
αα
2
2
2
,0 00 −=
+
−=
∂
∂
=
∂
∂
Euler-Lagrange Equation
−=
−=
∂
∂
−
∂
∂
=
sd
d
c
sd
xd
d
d
sd
d
cm
sd
xd
sd
xd
sd
xd
sd
d
cm
x
L
sd
xd
L
sd
d
sd
d
ττ
τ
α
β
β
α
αα
000 02
2
0 =
τ
α
d
xd
m
4-Vector Free Particle
Equation of MotionReturn to Table of Content
111. 04/08/15 111
SOLO
Classic Electrodynamics
Start with Microscopic Maxwell’s Equations in Gaussian Coordinates:
eE ρπ4=⋅∇
Gauss’ Law (Electric)
j
ct
E
c
B
π41
=
∂
∂
−×∇
Ampère’ Law
(with Maxwell’s Extension)
0
1
=
∂
∂
+×∇
t
B
c
EFaraday’ Law of Induction
Gauss’ Law (Magnetic) 0=⋅∇ B
Lorentz Force Equation:
Electric Field Intensity
[statV .
cm-1
]
E
Magnetic Induction
[statV .
sec .
cm-2
= gauss]
B
ρe Charge density [statC .
cm-3
]
j
Current Density [statA .
cm-3
]
eF
Electromagnetic force [dynes]
u
Charge velocity [cm .
sec]
1 V = 1/3x10-2
statV
1 C = 3x109
statC
1 A= 3x109
statA
×+= B
c
u
EqFe
Classical Electromagnetic Theory
q electric charge [statC]
113. 04/08/15 113
SOLO
0
111
=
∂
∂
+×∇=×∇
∂
∂
+×∇=
∂
∂
+×∇
t
A
c
EA
tc
E
t
B
c
E
Therefore we can define a Potential φ, such that
We can define a vector such that0=⋅∇ B
0≡×∇⋅∇⇐×∇= AAB
A
0
1
≡∇×∇⇐−∇=
∂
∂
+ ϕϕ
t
A
c
E
and φ are not uniquely defined since
will give the same results for .
Such a transformation that doesn’t change the results is called a “Gauge
Transformation” on the Potentials.
( )BE
,
A
t
f
c
andfgradAA
∂
∂
−=+=
1
11 ϕϕ
ϕ∇−
∂
∂
−=
×∇=
t
A
c
E
AB
1
We obtained
Classical Electromagnetic Theory
Classic Electrodynamics
Electrodynamic Potentials and φA
114. 04/08/15 114
SOLO
Classical Electromagnetic Theory
j
ct
E
c
B
π41
=
∂
∂
−×∇From we obtain
ϕ∇−
∂
∂
−=
×∇=
t
A
c
E
AB
1
( ) j
c
A
t
A
ctc
A
tct
A
c
A
πϕϕ 41111 2
2
2
22
2
2
=
∇−
∂
∂
+
∂
∂
+⋅∇∇=
∂
∂
∇−
∂
∂
+×∇×∇
From we obtaineE ρπ4=⋅∇
eA
tc
ρπϕ 4
1 2
=∇−⋅∇
∂
∂
−
Since and φ are not uniquely defined, let add the following
relation:
A
0
1
=
∂
∂
+⋅∇
tc
A
ϕ
We obtain
Lorenz Condition
e
tc
j
c
A
t
A
c
ρπϕ
ϕ
π
4
1
41
2
2
2
2
2
2
2
2
=∇−
∂
∂
=∇−
∂
∂
Waveform Equations for
and φ.A
Ludwig Valentin
Lorenz
1829-1891
Classic Electrodynamics
115. 04/08/15 115
SOLO
0
1
=
∂
∂
+⋅∇
tc
A
ϕ Lorenz Condition
e
tc
j
c
A
t
A
c
ρπϕ
ϕ
π
4
1
41
2
2
2
2
2
2
2
2
=∇−
∂
∂
=∇−
∂
∂
Waveform Equations for
and φ.A
If we define the new Potentials through the relations
t
f
c
andfAA
∂
∂
−=∇+=
1
11 ϕϕ
To satisfy the Lorenz Condition
0
111
2
2
2
2
0
1
1 =
∂
∂
−∇+
∂
∂
+⋅∇=
∂
∂
+⋅∇
t
f
c
f
tc
A
tc
A
ϕϕ
0
1
2
2
2
2
=
∂
∂
−∇
t
f
c
fTherefore f must satisfy
Classical Electromagnetic Theory
Classic Electrodynamics
116. 116
SOLO
Energy and Momentum
( )
EJB
c
u
Eup e
Buu
Ju
e
ee
⋅=
×+⋅=
=×⋅
=
0
ρ
ρ
or
( ) ( ) ( )
( ) ( )[ ]
( )BE
c
t
B
BE
t
E
E
t
E
BEEB
c
E
t
E
c
B
c
EJp
t
B
c
E
BEBEEB
J
ct
E
c
B
e
e
×⋅∇−
∂
∂
⋅+⋅
∂
∂
−=
⋅
∂
∂
−×⋅∇−×∇⋅=
⋅
∂
∂
−×∇=⋅=
∂
∂
−=∇×
×⋅∇=∇×⋅−∇×⋅
+
∂
∂
=∇×
ππ
ππ
π
π
44
1
4
1
4
1
4
1
41
( )
( )
( )
( )
=⋅∇
=⋅∇
+
∂
∂
=×∇
∂
∂
−=×∇
0
4
41
1
BGM
EGE
J
ct
E
c
BA
t
B
c
EF
e
e
ρπ
π
Classical Electromagnetic Theory
( )BE
cBBEE
t
EJp e
×⋅∇−
⋅
+
⋅
∂
∂
−=⋅=
ππ 4224
1
The power density of the Lorentz Force the charge ρe
and velocity isu
117. 117
SOLO
Energy and Momentum (continue -1)
We identify the following quantities
EJe
⋅
⋅
∂
∂
=⋅= BB
t
pBBw mm
ππ 8
1
,
8
1
⋅
∂
∂
=⋅= EE
t
pEEw ee
ππ 8
1
,
8
1
( )BE
c
pR
×⋅∇=
π4
- Magnetic energy and power densities, respectively
(Energy transferred from the field to the particles)
- Electric energy and power densities, respectively
- (Energy transferred from the field to the particles)
- Radiation power density (Power lost through the
boundaries
( )EE
tt
E
E
⋅
∂
∂
=
∂
∂
⋅
2
1
( )BB
tt
B
B
⋅
∂
∂
=
∂
∂
⋅
2
1
-Power density of the current density eJ
Classical Electromagnetic Theory
( )BE
cBBEE
t
EJp e
×⋅∇−
⋅
+
⋅
∂
∂
−=⋅=
ππ 4224
1
Note: The minus sign means transfer of power from (loss) the electromagnetic field.
( )BE
c
S
×=
π4
: - Poynting power flux vector
118. 118
SOLO
Energy and Momentum (continue – 2)
Let integrate this equation over a constant volume V
=
∂
∂
∫∫ VV
td
d
t
Classical Electromagnetic Theory
( )BE
cBBEE
t
EJp e
×⋅∇−
⋅
+
⋅
∂
∂
−=⋅=
πππ 488
PowerRadiationEM
V
PowerMagnetic
V
PowerEletrical
V
Powet
V
e vd
c
BE
cvd
BB
t
vd
EE
t
vdEJ ∫∫∫∫
×
⋅∇−
⋅
∂
∂
−
⋅
∂
∂
−=⋅
πππ 488
2
119. 04/08/15 119
SOLO
Electromagnetic Stress
Lorentz Force Density
( )
( )
( )
( )
=⋅∇
=⋅∇
+
∂
∂
=×∇
∂
∂
−=×∇
0
4
41
1
BGM
EGE
J
ct
E
c
BA
t
B
c
EF
e
e
ρπ
π
Electric Field Intensity [statV .
cm-1
]E
Magnetic Induction [statV .
sec .
cm-2
= gauss]B
ρe Charge density [statC .
cm-3
]
eJ
Current Density [statA .
cm-3
]
Maxwell Electromagnetic Stress
Start with Maxwell Equations in Gaussian Coordinates
uJ
BJ
c
Ef
ee
eee
ρ
ρ
=
×+=
1
ef
Electromagnetic force density [dynes .
cm-3
]
u
Charge velocity [cm .
sec]
( ) ( )
( ) ( ) ( ) ( ) B
t
E
c
BBBB
t
B
E
c
EEEE
B
t
E
c
BBEEfe
×
∂
∂
−
⋅∇+××∇+
∂
∂
×−×∇×−+⋅∇=
×
∂
∂
−××∇+⋅∇=
1
4
1
4
11
4
1
1
4
1
4
1
4
1
0
0
πππ
πππ
( ) ( )[ ] ( ) ( )
∂
∂
×+×
∂
∂
−
⋅∇−×∇×−⋅∇−×∇×−=
t
B
EB
t
E
c
BBBBEEEEfe
1
4
1
4
1
4
1
0
πππ
1 V = 1/3x10-2
statV
1 C = 3x109
statC
1 A= 3x109
statA
uJ
BJ
c
Ef
ee
eee
ρ
ρ
=
×+=
1
120. 04/08/15 120
SOLO
Electromagnetic Stress
Maxwell Electromagnetic Stress
( ) ( )[ ] ( ) ( )[ ]
∂
∂
×+×
∂
∂
−×∇×−⋅∇+×∇×−⋅∇=
t
B
EB
t
E
c
BBBBEEEEfe
1
4
1
4
1
4
1
πππ
Use to get( ) ( ) ( )BABABA B
∇⋅−⋅∇=×∇×
( ) ( ) ( )EEEEEE E
∇⋅−⋅∇=×∇×
( ) ( )[ ] ( ) ( )[ ] ( ) ( ) ( )EEIEEEEEEEEEEEE EE
⋅∇⋅−⋅∇=⋅∇−∇⋅+⋅∇=×∇×−⋅∇
and
( ) ( )[ ] ( ) ( )[ ] ( ) ( )
⋅−⋅∇=⋅∇−∇⋅+⋅∇=×∇×−⋅∇ EEIEEEEEEEEEEEE
2
1
2
1
therefore
where the unit dyadic.
=
100
010
001
I
( ) ( )[ ] ( ) ( )[ ] ( ) ( )
⋅−⋅∇=⋅∇−∇⋅+⋅∇=×∇×−⋅∇ BBIBBBBBBBBBBBB
2
1
2
1
On the same
121. 04/08/15 121
SOLO
Electromagnetic Stress
Maxwell Electromagnetic Stress
( ) ( )
×
∂
∂
−
⋅−⋅∇+
⋅−⋅∇=
c
BE
t
BBIBBEEIEEfe
πππ 42
1
4
1
2
1
4
1
Define
( )
⋅−= EEIEETe
2
1
4
1
:
π
( )
⋅−= BBIBBTm
2
1
4
1
:
π
( )
⋅+⋅−+=+= BBEEIBBEETTT me
2
1
4
1
:
π
[ ]2−
⋅cmdynesTm
. - Magnetic Stress Tensor
[ ]2−
⋅cmdynesTe
. - Electric Stress Tensor
[ ]2−
⋅+≡ cmdynesTTT me
. - Electromagnetic Stress Tensor
c
BE
G
π4
:
×
=
[ ]213
secsec −−−
⋅⋅=⋅⋅ cmergcmdynesG
- Momentum Density Vector
t
S
Tfe
∂
∂
−⋅∇=
Return to Relativistic EM Stress
Editor's Notes
J. V. José, E. J. Saletan, “Classical Dynamics – A Contemporary Approach”, Cambridge University Press, 1998, pp. 67-68
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989
J.V. José, E. J. Saletan, “Classical Dynamics – A Contemporary Approach”, Cambridge University, 1998, pp. 124-128
Hero’s proof is described in “Optics”, M.V. Klein, T.E. Furtak. Pp. 3-5
A.C. Tribble, “Princeton Guide to Advanced Physics”, Princeton University Press, 1996, pp. 37-42
A.C. Tribble, “Princeton Guide to Advanced Physics”, Princeton University Press, 1996, pp. 37-42
A.C. Tribble, “Princeton Guide to Advanced Physics”, Princeton University Press, 1996, pp. 37-42
A.C. Tribble, “Princeton Guide to Advanced Physics”, Princeton University Press, 1996, pp. 37-42
A.C. Tribble, “Princeton Guide to Advanced Physics”, Princeton University Press, 1996, pp. 37-42
A.C. Tribble, “Princeton Guide to Advanced Physics”, Princeton University Press, 1996, pp. 37-42
C. Møller, “The Theory of Relativity”, 2nd Ed., Clarendon Press, Oxford, 1972, pp. 102-107
C. Møller, “The Theory of Relativity”, 2nd Ed., Clarendon Press, Oxford, 1972, pp. 102-107
C. Møller, “The Theory of Relativity”, 2nd Ed., Clarendon Press, Oxford, 1972, pp. 102-107
C. Møller, “The Theory of Relativity”, 2nd Ed., Clarendon Press, Oxford, 1972, pp. 102-107
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 583-585
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 583-585
http://en.wikipedia.org/wiki/Maxwell&apos;s_equations
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 553-558
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 553-558
http://en.wikipedia.org/wiki/Maxwell&apos;s_equations
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 553-558
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 553-558
J. Schwinger, L.L. DeRaad, Jr., K.A. Milton, Wu-yang Tsai, “Classical Electrodynamics”, Perseus Books, 1998, pp. 64-65
J. Schwinger, L.L. DeRaad, Jr., K.A. Milton, Wu-yang Tsai, “Classical Electrodynamics”, Perseus Books, 1998, pp. 64-65
J. Schwinger, L.L. DeRaad, Jr., K.A. Milton, Wu-yang Tsai, “Classical Electrodynamics”, Perseus Books, 1998, pp. 64-65
http://en.wikipedia.org/wiki/Maxwell&apos;s_equations
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999
C. Möller, “The Theory of Relativity”, Clarendon Press Oxford, 2nd Ed., 1972, pp. 162-167
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975, pp. 69
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968
A.O. Barut, “Electrodynamics and Classical Theory of Fields and Particles”, Dover, 1964, pp.93-103
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 605-608
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975, pg. 69
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975, pg. 69
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 553-558
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 553-558
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 553-558
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 553-558
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 553-558
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 553-558
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 553-558
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 553-558
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 553-558
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 543-548, 558-561
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 543-548, 558-561
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 543-548, 558-561
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 543-548, 558-561
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 543-548, 558-561
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 543-548, 558-561
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 553-558
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 553-558
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 553-558
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 553-558
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 553-558
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 553-558
C. Möller, “The Theory of Relativity”, Clarendon Press Oxford, 2nd Ed., 1972, pp. 165-167
C. Möller, “The Theory of Relativity”, Clarendon Press Oxford, 2nd Ed., 1972, pp. 165-167
http://en.wikipedia.org/wiki/Maxwell&apos;s_equations
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999
http://en.wikipedia.org/wiki/Maxwell&apos;s_equations
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999
http://en.wikipedia.org/wiki/Maxwell&apos;s_equations
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999
http://en.wikipedia.org/wiki/Maxwell&apos;s_equations
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975, pg. 46
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 583-585
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 583-585
W.K.H. Panofsky, M. Phillips, “Classical Electricity and Magnetism”, Addison Wesley, 2nd Ed., pp. 427 - 430
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 583-585
W.K.H. Panofsky, M. Phillips, “Classical Electricity and Magnetism”, Addison Wesley, 2nd Ed., pp. 427 - 430
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 583-585
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975, pp. 60-62
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975, pp. 60-62
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975, pp. 60-62
C. Möller, “The Theory of Relativity”, Clarendon Press Oxford, 2nd Ed., 1972, pp. 162-167
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975, pp. 69
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968
A.O. Barut, “Electrodynamics and Classical Theory of Fields and Particles”, Dover, 1964, pp.93-103
J.D. Jackson, “Classical Electrodynamics”, John Wiley & Sons, 3th Ed., 1999, pp. 605-608
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975, pg. 69
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975, pg. 69
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975, pg. 69
L.D. Landau, E.M. Lifshitz, “The Classical Theory of Fields”, 4th Revised English Edition, Pergamon Press, 1975, pg. 69
H. Goldstein, “Classical Mechanics”, 2nd Ed., Addison Wesley, 1980
H. Goldstein, “Classical Mechanics”, 2nd Ed., Addison Wesley, 1980
H. Goldstein, “Classical Mechanics”, 2nd Ed., Addison Wesley, 1980
I.M. Gelfand, S.V.Fomin, “Calculus of Variations”, Prentice-Hall, 1963, pp. 81-83, 176-179
A.O. Barut, “Electrodynamics and Classical Theory of Particles”, Dover, 1964, pp. 103-105
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989, pp. 201-207
H. Goldstein, “Classical Mechanics”, 2nd Ed., Addison Wesley, 1980, pp.590-591
T. Frankel, “The Geometry of Physics – An Introduction”, Cambridge University, 1997, pp. 523 - 529
I.M. Gelfand, S.V.Fomin, “Calculus of Variations”, Prentice-Hall, 1963, pp. 81-83, 176-179
A.O. Barut, “Electrodynamics and Classical Theory of Particles”, Dover, 1964, pp. 103-105
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989, pp. 201-207
H. Goldstein, “Classical Mechanics”, 2nd Ed., Addison Wesley, 1980, pp.590-591
I.M. Gelfand, S.V.Fomin, “Calculus of Variations”, Prentice-Hall, 1963, pp. 81-83, 176-179
A.O. Barut, “Electrodynamics and Classical Theory of Particles”, Dover, 1964, pp. 103-105
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989, pp. 201-207
H. Goldstein, “Classical Mechanics”, 2nd Ed., Addison Wesley, 1980, pp.590-591
I.M. Gelfand, S.V.Fomin, “Calculus of Variations”, Prentice-Hall, 1963, pp. 81-83, 176-179
A.O. Barut, “Electrodynamics and Classical Theory of Particles”, Dover, 1964, pp. 103-105
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989, pp. 201-207
H. Goldstein, “Classical Mechanics”, 2nd Ed., Addison Wesley, 1980, pp.590-591
I.M. Gelfand, S.V.Fomin, “Calculus of Variations”, Prentice-Hall, 1963, pp. 81-83, 176-179
A.O. Barut, “Electrodynamics and Classical Theory of Particles”, Dover, 1964, pp. 103-105
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989, pp. 201-207
H. Goldstein, “Classical Mechanics”, 2nd Ed., Addison Wesley, 1980, pp.590-591
I.M. Gelfand, S.V.Fomin, “Calculus of Variations”, Prentice-Hall, 1963, pp. 81-83, 176-179
A.O. Barut, “Electrodynamics and Classical Theory of Particles”, Dover, 1964, pp. 103-105
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989, pp. 201-207
H. Goldstein, “Classical Mechanics”, 2nd Ed., Addison Wesley, 1980, pp.590-591
I.M. Gelfand, S.V.Fomin, “Calculus of Variations”, Prentice-Hall, 1963, pp. 81-83, 176-179
A.O. Barut, “Electrodynamics and Classical Theory of Particles”, Dover, 1964, pp. 103-105
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989, pp. 201-207
H. Goldstein, “Classical Mechanics”, 2nd Ed., Addison Wesley, 1980, pp.590-591
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989
H. Sagan, “Boundary and Eigenvalue Problems in Mathematical Physics”, John Wiley & Sons, 1961, Dover, 1989, pp. 34-49
B.L. Moiseiwitsch, “Variational Principles”, John Wiley & Sons, 1966, Dover, 2004, pp. 91-94
P. R. Wallace, “Mathematical Analysis of Physical Properties”, Dover, 1972, 1984, “The Vibrating String”, pp. 5-65
H. Sagan, “Boundary and Eigenvalue Problems in Mathematical Physics”, John Wiley & Sons, 1961, Dover, 1989, pp. 34-49
B.L. Moiseiwitsch, “Variational Principles”, John Wiley & Sons, 1966, Dover, 2004, pp. 91-94
P. R. Wallace, “Mathematical Analysis of Physical Properties”, Dover, 1972, 1984, “The Vibrating String”, pp. 5-65
H. Sagan, “Boundary and Eigenvalue Problems in Mathematical Physics”, John Wiley & Sons, 1961, Dover, 1989, pp. 34-49
B.L. Moiseiwitsch, “Variational Principles”, John Wiley & Sons, 1966, Dover, 2004, pp. 91-94
P. R. Wallace, “Mathematical Analysis of Physical Properties”, Dover, 1972, 1984, “The Vibrating String”, pp. 5-65
H. Sagan, “Boundary and Eigenvalue Problems in Mathematical Physics”, John Wiley & Sons, 1961, Dover, 1989, pp. 49-65
B.L. Moiseiwitsch, “Variational Principles”, John Wiley & Sons, 1966, Dover, 2004, pp. 94-95
H. Sagan, “Boundary and Eigenvalue Problems in Mathematical Physics”, John Wiley & Sons, 1961, Dover, 1989, pp. 49-65
B.L. Moiseiwitsch, “Variational Principles”, John Wiley & Sons, 1966, Dover, 2004, pp. 94-95
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
Asher Yahalom, “A Simpler Eulerian Variational Principle for Barotropic Fluids”, February 2, 2008,
http://arxiv.org/pdf/physics/9906050.pdf
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
Asher Yahalom, “A Simpler Eulerian Variational Principle for Barotropic Fluids”, February 2, 2008,
http://arxiv.org/pdf/physics/9906050.pdf
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
Asher Yahalom, “A Simpler Eulerian Variational Principle for Barotropic Fluids”, February 2, 2008,
http://arxiv.org/pdf/physics/9906050.pdf
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
Asher Yahalom, “A Simpler Eulerian Variational Principle for Barotropic Fluids”, February 2, 2008,
http://arxiv.org/pdf/physics/9906050.pdf
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
Asher Yahalom, “A Simpler Eulerian Variational Principle for Barotropic Fluids”, February 2, 2008,
http://arxiv.org/pdf/physics/9906050.pdf
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
Asher Yahalom, “A Simpler Eulerian Variational Principle for Barotropic Fluids”, February 2, 2008,
http://arxiv.org/pdf/physics/9906050.pdf
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
Asher Yahalom, “A Simpler Eulerian Variational Principle for Barotropic Fluids”, February 2, 2008,
http://arxiv.org/pdf/physics/9906050.pdf
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
Asher Yahalom, “A Simpler Eulerian Variational Principle for Barotropic Fluids”, February 2, 2008,
http://arxiv.org/pdf/physics/9906050.pdf
W. Yourgrau, S. Mandelstam, “Variational Principles in Dynamics and Quantum Theory”, Dover, 1968, § 13, “Variational Principles in Hydrodynamics”, pp. 142-161
M. Stone, P. Goldbart, “Mathematics for Physics”, Pimander-Casaubon Publishers, Ch.1, “Calculus of Variations”, Problem 1-12, pg. 50
N.N. Moiseyev, V.V. Rumyantsev, “Dynamic Stability of Bodies Containing Fluids”, Springer-Verlag, 1968
P. R. Wallace, ‘Mathematical Analysis of Physical Problems”, Dover, 1972, 1984, pp. 232 - 239
B. L. Moiseiwitsch, “Variational Principles”, John Wiley & Sons, 1966, Dover, 2004, pp. 96 – 100
H. Goldstein, “Classical Mechanics”, Addison Wesley, 2nd Ed., 1980, Appendix E, pp. 616 - 619
P. R. Wallace, ‘Mathematical Analysis of Physical Problems”, Dover, 1972, 1984, pp. 232 - 239
B. L. Moiseiwitsch, “Variational Principles”, John Wiley & Sons, 1966, Dover, 2004, pp. 96 – 100
H. Goldstein, “Classical Mechanics”, Addison Wesley, 2nd Ed., 1980, Appendix E, pp. 616 - 619
P. R. Wallace, ‘Mathematical Analysis of Physical Problems”, Dover, 1972, 1984, pp. 232 - 239
B. L. Moiseiwitsch, “Variational Principles”, John Wiley & Sons, 1966, Dover, 2004, pp. 96 – 100
H. Goldstein, “Classical Mechanics”, Addison Wesley, 2nd Ed., 1980, Appendix E, pp. 616 - 619
P. R. Wallace, ‘Mathematical Analysis of Physical Problems”, Dover, 1972, 1984, pp. 232 - 239
B. L. Moiseiwitsch, “Variational Principles”, John Wiley & Sons, 1966, Dover, 2004, pp. 96 – 100
H. Goldstein, “Classical Mechanics”, Addison Wesley, 2nd Ed., 1980, Appendix E, pp. 616 - 619
P. R. Wallace, ‘Mathematical Analysis of Physical Problems”, Dover, 1972, 1984, pp. 232 - 239
B. L. Moiseiwitsch, “Variational Principles”, John Wiley & Sons, 1966, Dover, 2004, pp. 96 – 100
H. Goldstein, “Classical Mechanics”, Addison Wesley, 2nd Ed., 1980, Appendix E, pp. 616 - 619
P. R. Wallace, ‘Mathematical Analysis of Physical Problems”, Dover, 1972, 1984, pp. 232 - 239
B. L. Moiseiwitsch, “Variational Principles”, John Wiley & Sons, 1966, Dover, 2004, pp. 96 – 100
H. Goldstein, “Classical Mechanics”, Addison Wesley, 2nd Ed., 1980, Appendix E, pp. 616 - 619
P. R. Wallace, ‘Mathematical Analysis of Physical Problems”, Dover, 1972, 1984, pp. 232 - 239
B. L. Moiseiwitsch, “Variational Principles”, John Wiley & Sons, 1966, Dover, 2004, pp. 96 – 100
H. Goldstein, “Classical Mechanics”, Addison Wesley, 2nd Ed., 1980, Appendix E, pp. 616 - 619
P. R. Wallace, ‘Mathematical Analysis of Physical Problems”, Dover, 1972, 1984, pp. 232 - 239
B. L. Moiseiwitsch, “Variational Principles”, John Wiley & Sons, 1966, Dover, 2004, pp. 96 – 100
H. Goldstein, “Classical Mechanics”, Addison Wesley, 2nd Ed., 1980, Appendix E, pp. 616 - 619
I.M. Gelfand, S.V.Fomin, “Calculus of Variations”, Prentice-Hall, 1963, pp. 81-83, 176-179
A.O. Barut, “Electrodynamics and Classical Theory of Particles”, Dover, 1964, pp. 103-105
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989, pp. 201-207
H. Goldstein, “Classical Mechanics”, 2nd Ed., Addison Wesley, 1980, pp.590-591
I.M. Gelfand, S.V.Fomin, “Calculus of Variations”, Prentice-Hall, 1963, pp. 81-83, 176-179
A.O. Barut, “Electrodynamics and Classical Theory of Particles”, Dover, 1964, pp. 103-105
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989, pp. 201-207
H. Goldstein, “Classical Mechanics”, 2nd Ed., Addison Wesley, 1980, pp.590-591
I.M. Gelfand, S.V.Fomin, “Calculus of Variations”, Prentice-Hall, 1963, pp. 81-83, 176-179
A.O. Barut, “Electrodynamics and Classical Theory of Particles”, Dover, 1964, pp. 103-105
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989, pp. 201-207
H. Goldstein, “Classical Mechanics”, 2nd Ed., Addison Wesley, 1980, pp.590-591
I.M. Gelfand, S.V.Fomin, “Calculus of Variations”, Prentice-Hall, 1963, pp. 81-83, 176-179
A.O. Barut, “Electrodynamics and Classical Theory of Particles”, Dover, 1964, pp. 103-105
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989, pp. 201-207
H. Goldstein, “Classical Mechanics”, 2nd Ed., Addison Wesley, 1980, pp.590-591
I.M. Gelfand, S.V.Fomin, “Calculus of Variations”, Prentice-Hall, 1963, pp. 81-83, 176-179
A.O. Barut, “Electrodynamics and Classical Theory of Particles”, Dover, 1964, pp. 103-105
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989, pp. 201-207
H. Goldstein, “Classical Mechanics”, 2nd Ed., Addison Wesley, 1980, pp.590-591
I.M. Gelfand, S.V.Fomin, “Calculus of Variations”, Prentice-Hall, 1963, pp. 81-83, 176-179
A.O. Barut, “Electrodynamics and Classical Theory of Particles”, Dover, 1964, pp. 103-105
D. Lovelock, H. Rund, “Tensors, Differential Forms, and Variational Principles”, Dover, 1975, 1989, pp. 201-207
H. Goldstein, “Classical Mechanics”, 2nd Ed., Addison Wesley, 1980, pp.590-591