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1. SMKN 1 BERAU
FLUID STATICS

2. Adaptif
DENSITY
V
m
=ρ
Hal.: 2
ISI DENGAN JUDUL HALAMAN TERKAIT
Density of a substance is defined as the ratio of mass
substance with its volume
Note:
ρ = density of substance (kg/m3
)
m = mass of substance kg
V = volume of substance m3
Density unit is often expressed I g/cm3
1 g/cm3
= 1000 kg/m3

3. Adaptif
area
force
pressure =
A
F
p =
Hal.: 3
ISI DENGAN JUDUL HALAMAN TERKAIT
PRESSURE
Note:
p = pressure (N/m2
) or Pascal (Pa)
F = force N
A = area of pressure m2
F = w
A
Pressure are force per unit area

4. Adaptif
HYDROSTATIC PRESSURE
hgp ρ=
Hal.: 4
ISI DENGAN JUDUL HALAMAN TERKAIT
Fluid pressure at rest is called hydrostatic pressure.
Note:
ρ = density of liquid (kg/m2
)
g = earth gravitational acceleration (m/s2
)
h = depth of liquid measured from its surface
to point the pressure is give (m)
px = hydrostatic pressure (N/m2
)
Based on the formula of hydrostatic pressure above, found that
hydrostatic pressure depends on the liquids density, height or
depth of liquids, and earth gravitational acceleration
x
h
x
water

5. Adaptif
HYDROSTATIC PRESSURE
Hal.: 5
ISI DENGAN JUDUL HALAMAN TERKAIT
The strenght of water
sprays or liquids sprays
is determined by the
ammount of pressure in
the water or liquids. It
means the deeper a
location in the water or
liquids froms its surface
then the large its
hydrostatic pressure
Scientific activity
water
hole
water spray

6. Adaptif
FUNDAMENTAL LAW OF HYDROSTATIC
Hal.: 6
ISI DENGAN JUDUL HALAMAN TERKAIT
Source: http://superphysics.netfirms.com/t240754a.jpg
Every point located on a plane in a liquid have the same
hydrostatic pressure

7. Adaptif
FUNDAMENTAL LAW OF HYDROSTATIC
Hal.: 7
ISI DENGAN JUDUL HALAMAN TERKAIT
hA hB
oil water
A B
A U-shaped tube contains oil and water, as shown in below figure:
Point A and B are both lie on the
same plane and type of liquid.
According to fundamental law of
hydrostatics, then both points
have the same pressure, so that:
pA = pB
ρoil g hA = ρwater g hB
ρoil hA = ρwater hB
minyak
B
A
oil ρ
h
h
ρ =
Note:
ρoil = oil density
ρwater = water density
hA = oil colum height
hB = water colum height

8. Adaptif
PASCAL’S LAW
Hal.: 8
ISI DENGAN JUDUL HALAMAN TERKAIT
The pressure applied to an enclosed fluid is transmitted
equally in all directions and to all parts of the container
Application example of Pascal’s law
Principle of hydroulic jack
2
1
1
2 A
A
F
F =
Note:
F1 = force on A1 (N)
F2 = force on A2 (N)
A1 = section area 1 (m2
)
A2 = section area 2 (m2
)
A2
F2
A1
F1
Source: http://home.wxs.nl/~brink494/hydr.htg/pascal.gif

9. Adaptif
ARCHIMEDES’S LAW
Hal.: 9
ISI DENGAN JUDUL HALAMAN TERKAIT
A body that is partly, or entirely, immersed in water or any
fluids will experience the buoyancy force that is equal to the
weight of the fluid displaced by the body
FA = wbf
Note:
FA = buoyancy force
wbf = the weight of fluid displaced
FA = ρf Vbf g Note:
ρf = fluid density (liquid)
Vbf = Volume of liquid displaced
g = earth gravitational acceleration

10. Adaptif
ARCHIMEDES’S LAW
Hal.: 10
ISI DENGAN JUDUL HALAMAN TERKAIT
The singking body
FA < w
mf g < mb g
Vf ρf g < Vb ρb g
ρf < ρb
Note:
mb = mass of body
mf = transfered liquid mass
Vb = volume of body
Vf = transfered liquid volume
ρb = the density of body
ρf = the density of liquid
A body is said sinking if it is
completely immersed and be
on the bottom of liquid.
w
FA
water

11. Adaptif
ARCHIMEDES’S LAW
Hal.: 11
ISI DENGAN JUDUL HALAMAN TERKAIT
The suspending body
FA = w
mf g = mb g
Vf ρf g = Vb ρb g
ρf = ρb
A body is said suspending if it is
completely immersed but does
not reach the bottom of liquid.
w
FA
water
Note:
mb = mass of body
mf = transfered liquid mass
Vb = volume of body
Vf = transfered liquid volume
ρb = the density of body
ρf = the density of liquid

12. Adaptif
ARCHIMEDES’S LAW
f
b
f
b ρ
V
V
ρ =
Hal.: 12
ISI DENGAN JUDUL HALAMAN TERKAIT
The floating body
A body is said floating if it is partly
immersed a liquid.
FA = w
mf g = mb g
Vf ρf g = Vb ρb g
because Vf < Vb
then ρf > ρb
w
FA
water

13. Adaptif
SURFACE TENSION OF LIQUID
Hal.: 13
ISI DENGAN JUDUL HALAMAN TERKAIT
The attractive force among like particles is called
cohesion while that of among unlike particles is
called adhesion.
Each particle in a liquid is attracted with equal
force to all direction by the particles near it, so that the
resultant force applied on the particle is equel to zero.

14. Adaptif

F
=γ
Hal.: 14
ISI DENGAN JUDUL HALAMAN TERKAIT
SURFACE TENSION OF LIQUID
Surface tension can be defined as the magnitude of
force experienced at liquid surface per unit length.
lenght
forceF
tensionsurface
=
=
=

γ
Note:
w2
w1
One layer of soap water
water

15. Adaptif
CAPILLARITY
Hal.: 15
ISI DENGAN JUDUL HALAMAN TERKAIT
A phenomenon of raising and descending of liquid in
capillary pipe is called cpillarity
The water in capillary pipe will continue to raise until the equilib-
rium is reached, that is water weight displaced is balanced with
adhesion force. While the descending of mercury in capillary pipe
occurs because the cohesion among mercury particles is greater
than the adhesion between mercury particles and glass particles.
cohesion < adhesion
mercurywater
cohesion > adhesion

16. Adaptif
CAPILLARITY
hgρ
cosθ2γ
=h
Hal.: 16
ISI DENGAN JUDUL HALAMAN TERKAIT
The amount of liquid increase or decrease in capillary pipe is
determined by the equation below.
Note:
h = increase or decrease of liquid level (m)
γ = surface tention (N/m)
ρ = liquid density (kg/m3
)
θ = contact angle
g = gravitational acceleration (m/s2
)
r = the radius of capillary pipe (m)

17. Adaptif
VISCOSITY OF FLUID AND STOKES LAW
Hal.: 17
ISI DENGAN JUDUL HALAMAN TERKAIT
The maesure of viscosity of a liquid is expressed by viscosity.
Ff = k η v
Note:
Ff = friction force of liquid (N)
k = coefficient (depends on object geometric shape)
η = coefficient viscosity (Pa s)
v = kecepatan gerak benda (m/s)
The equation of friction force in fluid for sperical objects is
formulated as follows.
Ff = 6 k r η v

18. Adaptif
VISCOSITY OF FLUID AND STOKES LAW
Hal.: 18
ISI DENGAN JUDUL HALAMAN TERKAIT
w = m g
FA
fFA
arah gerak
Attention picture this below!
At the moment the object moving
at terminal velocity, on the object
act three force, those are weight,
buoyancy force exerted by fluid,
and friction force of fluid.
ΣF = 0
+ m g – FA – Ff = 0
m g – FA = Ff
Ff = m g – Ff
minyak

19. Adaptif
VISCOSITY OF FLUID AND STOKES
LAW
Hal.: 19
ISI DENGAN JUDUL HALAMAN TERKAIT
( )fbT ρρ
η
gr
v −=
2
9
2
Note:
vT = terminal velocity (m/s)
η = viskositas fluida (Ns/m2
)
ρb = dencity of body (kg/m3
)
ρf = dencity of fluid (kg/m3
)
g = gravitational acceleration (m/s2
)
r = radius of sphere (m)

20. AdaptifHal.: 20
ISI DENGAN JUDUL HALAMAN TERKAIT
TERIMA KASIH