Newton's three laws of motion describe the relationship between forces and motion. The first law states that an object at rest stays at rest or an object in motion stays in motion with the same speed and in the same direction unless acted upon by an external force. The second law states that the acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object. The third law states that for every action, there is an equal and opposite reaction. Newton compiled his three laws of motion in his work Philosophiæ Naturalis Principia Mathematica, published in 1687.

1. Newtons three laws of motion
around us

2. Newton's laws of motion are
three physical laws that
together laid the foundation for
classical mechanics. They
describe the relationship
between a body and the forces
acting upon it, and its motion in
response to said forces. They
have been expressed in several
different ways over nearly three
centuries, and can be
summarised as follows:
First law: When viewed in an
inertial reference frame, an
object either remains at rest or
continues to move at a constant
velocity, unless acted upon by
an external force.
Secod law: F = ma. The vector
sum of the forces F on an object
is equal to the mass m of that
object multiplied by the
acceleration vector a of the
object.
Third law: When one body
exerts a force on a second body,
the second body simultaneously
exerts a force equal in
magnitude and opposite in
direction on the first body.
The three laws of motion were
first compiled by Isaac Newton
in his Philosophiæ Naturalis
Principia Mathematica
(Mathematical Principles of
Natural Philosophy), first
published in 1687.Newton used
them to explain and investigate
the motion of many physical
objects and systems. For
example, in the third volume of
the text, Newton showed that
these laws of motion, combined
with his law of universal
gravitation, explained Kepler's
laws of planetary motion.

3. Sir Isaac Newton[ 25 December 1642 – 20 March 1727] was an English physicist and mathematician
(described in his own day as a "natural philosopher") who is widely recognised as one of the most
influential scientists of all time and as a key figure in the scientific revolution. His book Philosophiæ
Naturalis Principia Mathematica ("Mathematical Principles of Natural Philosophy"), first published in
1687, laid the foundations for classical mechanics. Newton also made seminal contributions to optics
and shares credit with Gottfried Leibniz for the invention of calculus.
The initial stage in the development of classical mechanics is often referred to as Newtonian
mechanics, and is associated with the physical concepts employed by and the mathematical
methods invented by Newton himself, in parallel with Leibniz, and others. This is further
described in the following sections. Later, more abstract and general methods were
developed, leading to reformulations of classical mechanics known as Lagrangian mechanics
and Hamiltonian mechanics. These advances were largely made in the 18th and 19th
centuries, and they extend substantially beyond Newton's work, particularly through their use
of analytical mechanics. Ultimately, the mathematics developed for these were central to the
creation of quantum mechanics.

4. WHY ARE NEWTONS LAWS OF MOTION
IMPORTANT
Newton first published his three laws of motion in 1687,& physics
students have been learning them in class ever since.They are
important to us because:
They work around
They represent mankinds first great success at describing diverse
aspects of nature with simple mathemitacal formulas.
They form the most intuitively appealing physical theory.
They lay the groundwork for later physics development

5. NEWTONS LAW'S WORK
Nature has been superseded by special relativity, quantum mechanics, & field
theory.Newton's law's fail miserably inside molecules & in distant outer space , in
fact they fail to even exolain some important features of classical
electromagnetism.However , there's a catch ; all these other theories reduce to
Newton's laws the realm of everyday's life.For a wide variety of situations,
Newton's law work just fine.This is why physicists didn't discover any problems
with them for over two hundred years. Newton's laws can predict the motion &
interactions of objects well enough to:
Build & navigate spaceships
Simulate car crashes
Measure the mass of the earth & other solar system bodies
Explain how airplains generate lift
Improve your athletic abilities
Nearly everything we experience in dialy life that involves motion can be explained
by Newton's laws in very accurate ways,& nearly you use in dialy life was designed
with Newton's laws in mind

6. NEWTON'S LAWS ARE A TRIUMPH FOR
HUMANITY
Newton's laws were not the first mathematical description of the universe.People
have actually been using math to predict the movement of the planets since
claudius ptolemaeus developed his model in the second century AD.This system
was eventually replaced with the Copernican system & even later by Kepler's laws
However, these systems all had numerous 7 arbitary set of rules.they worked,but
made very little sense.Newton's laws of motion (along with his law of universal
gravitation,which gave the appropriate form of the force to use in the second law)
were able to explain planetary motion with fewer concepts,those same three laws
applied to things on earth as well.
Newton also showed that the same laws govern celestial motion & terrestrial
motion.For all of history until that point,people hadbelieved that the heavens were
so sacred that they constituted the totally different realm.Newton proved
otherwise! Newton showed that the human brain was capable of understanding
deep properties of the natural world.This accomplishment was totally
unpresedented & it greatly influnced scientific & religious communities

7. NEWTON'S FIRST LAW OF MOTION
http://www.youtube.com/watch?v=OHw80HXSuAQ

8. In detail about 1st law
“ everybody presists in its state of being at rest or of moving straight forwars,
except insofar as it is compelled to change its state by force impressed” is the
defination of Newton's first law of motion.
The ancient greek philosopher Aristotle had the view that all objects have a
natural place in the universe;that heavy objects wanted to be at rest on the earth
& that light objects like smoke wanted to be at rest in the sky & the stars wanted
to remain in the heavens . He thought that a body was in its natural state when it
was at rest ,& for the body to move in a straight line at a constant speed an
external agent was needed to continually propel it,otherwise it would stop
moving. Galileo Galilei ,however ,realised that a force is necessary to change the
velocity of a body , that is accleration, but no force is needed to maintain its
velocity.in other words,Galileo stated that,in absence of a force,a moving object
will continue moving. The tendency of objects to resist changes in motion was
what Galileo called it INERTIA. This sight was refined by Newton, who made it
into his 1st law ,also known as the “LAW OF INERTIA”-NO FORCE MEANS NO
ACCLERATION, & hence the body will maintain its velocity. As Newton's 1st law is
a restatement of the law of inertia wich Galileo had already described, Newton
appropriately gave credit to Galileo.

9. Animated view of 1st law

10. Examples for inertia of motion
● A pearson riding a bicycle along a levelled road does not
come to rest immediately after he stops pedelling.Thus the
cycle continous to move due to inertia of motion .Finally it
comes to rest , after travelling some distance, because of
the friction exerted by the ground.

11. INERTIA & MASS
●
To change the velocity of a body , one has
to apply force. Consider 2 bodies of
unequal masses initially at rest. If you push
the bodies equally hard for equal time
,both'll start moving .But the lighter one
starts with larger velocity & the heavier
one starts with smaller velocity. Thus the
heavier one has resisted the change of
more effectively than the lighter one.
Hence heavier bodies have larger inertia
than lighter ones. So ,MASS IS A
QUANTATIVE MEASURE OF INERTIA .

12. NEWTONS SECOND LAW OF MOTION
“ THE CHANGE OF MOMENTUM OF A BODY IS A PROPORTIONAL TO THE MOTIVE
FORCE IMPRESSED ON THE BODY, & HAPPENS ALONG THE STRAIGHT LINE ON
WHICH THAT IMPULSE IS IMPRESSED.” is the defination of Newton's 2nd law of
motion.
Motte's 1729 translation of Newtons Latin continued with newtons commentary on
the second law of motion , reading ;
“ IF A FORCE GENERATES A MOTION , A DOUBLE FORCE WILL GENERATE DOUBLE
THE MOTION, A TRIPLE FORCE TRIPLE THE MOTION, WEATHER THAT FORCE BE
IMPRESSED ALTOGETHER AT ONCE, OR GRADUALLY AND SUCCESSIVELY .AND
THIS MOTION (BEING ALWAYS DIRECTED THE SAME WAY WITH THE GENERATING
FORCE), IF THE BODY MOVED BEFORE IS ADDED TO OR SUBTRACTED FROM THE
FORMAL MOTION, ACCORDING AS THEY DIRECTLY CONSPIRE WITH OR ARE
DIRECTLY CONTARY TO EACH OTHER; OR OBLIQUELY JOINED , WHEN ARE
OBLIQUE, SO AS TO PRODUCE A NEW MOTION COMPOUNDED FROM
DETERMINATION OF BOTH

13. GRAVITATIONAL
UNITS OF FORCE
● SI unit of force is NEWTON & is denoted by N.
● IN c.g.s system the unit of force is called DYNE.
● Newton & dyne are called absolute values of force.
ABSOLUTE &
● Gravitational force on an object of unit mass is known as gravitational unit of force.
● In MKS system, the gravitational unit of force is the KILO GRAM FORCE(kgf).In C.G.S
system ,the gravitational unit of force is the GRAM FORCE(gf).

14. LINEAR MOMENTUM
● The product of mass of a body & its velocity is called LINEAR
MOMENTUM or simply momentum of the body.If M is the mass of the
body ,V is the velocity , the momentum of the body is given by ;
● p=mv
● Linear momentum is a vector in the direction of velocity. Newton's
second law can be written in terms of momentum mv-mu divided by t
● Thus ,the alternate way of stating Newton's 2nd law is :
● The resultant force on a body is equal to the change in its linear
momentun per unit time.

15. TO DERIVE AN
EXPRESSION FOR FORCE
A force 'F' acts on a body of mass 'm' for a time 't' & changes its velocity
from 'u' to 'v.
The initial momentum of the body =mu
The final momentum of the body =mv
The change in momentum of the body in time 't' =mv-mu=m(v-u)
From Newton's 2nd law,
force=change in momentum by time = m(v-u), divided by t

16. IMPULSE OF A FORCE
When a tennis ball is hit by a player,or when a football, at rest , is
kicked towards a goal post, a large change in momentum is observed
in a very short interval. The force exerted by the floor or by the leg ,
acts only during a short period of contact with the ball. In such
cases, a very large magnitude force acts for a small interval of time.
Such forces are called IMPULSE FORCE.
Measurement of the magnitude of impulse force & time during which
it acts is very difficult. But the product of force & time can be
determined by measuring change in momentum of the body.
Ft=mv-mu
The quantity Ft is called IMPULSE OF FORCE. THE IMPULSE OF A
FORCE .The impulse of a force applied on a body is equal to the
change in the linear momentum of the body produced by the force.

17. NEWTON'S THIRD LSW OF
MOTION
“TO EVERY ACTION THERE IS ALWAYS OPPOSED AN EQUAL ACTION : OR THE
MUTUAL ACTIONS OF TWO BODIES UPON EACH OTHER ARE ALWAYS EQUAL, &
DIRECED TO CONTRARY PARTS “ is the defination of Newton's 3rd law of motion.
Newton used the 3rd law to derive the law of conservation of momentum; from a
deeper perspective ,however , conservation of momentum is the more fundamental
idea ,& holds in cases where Newton's 3rd law appears to fail, for the first time a
unified quantitative explanation for a wide range of physical phenomena.
In quantum mechanics concepts such as force , momentum ,& position are defined
by linear operators that operate on the quantum state; at speeds that are much lower
than the speed of light, Newton's laws are just as exact for these operators as they
are for classical objects. At speeds comparable to the speed of light , the 2nd law
holds in the original form F=dp/dt

18. CONTD..........
Click to A pair of forces exerted by two bodies on one another is
called an action reaction pair. The alternate statement of 3rd law is :
TO EVERY ACTION, THERE IS AN EQUAL & OPPOSITE REACTION
An example is that of a baloon-
A baloon forces the air in the downeard direction wgereas reaction to
this moves the baloon in upward direction.

19. CONSERVATION OF LINEAR MOMENTUM
According to Newton's 1st law, a particle remains at rest or moves with a constant
velocity if the total force acting on it is zero. In this case, linear momentum ,which is
mass times the velocity ,also remains a constant. Thus, linear momentum remains
constant in the absence of external force. This is true in case of system of particles
as well. We define linear momentum of a system as the vector sum of the moments of
all the particles of the system. Then the law of conservation of linear momentum can
be stated as followed
If the net xternal force is on a system is zero , the linear momentum of the system
remains constant
If the momentum of some particle is increased ,then the momentum of some other
particle must decrease to keep the net momentum of the object a constant

20. EXAMPLE OF ROCKET
PROPULSION
The principle of rocket propulsion is based on the 3rd law of motion.
Rockets eject gases at high pressure through thrir lower ends. The
escaping gases exert reactional force on the rocket therby
acclerating the rocket . After complete burning of the fuel, the
compartment is detached from the rocket. Thus the rocket becomes
lighter 7 will have a greater accleration

21. DONE BY-
HARSHITH.K
9th' A' ROLL NO-22