Download - statis fluid
SMKN 1 BERAU
FLUID STATICS
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
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area
forcepressure =
A
Fp =
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
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HYDROSTATIC PRESSURE
h g p 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
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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
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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
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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
minyakB
Aoil ρ
h
hρ =
Note:ρoil = oil densityρwater = water densityhA = oil colum heighthB = water colum height
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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
21
12 A
A
FF =
Note:F1 = force on A1 (N)F2 = force on A2 (N)A1 = section area 1 (m2)A2 = section area 2 (m2)
A2
F2A1
F1
Source: http://home.wxs.nl/~brink494/hydr.htg/pascal.gif
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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 = wbfNote:FA = buoyancy force wbf = the weight of fluid displaced
FA = ρf Vbf g Note:ρf = fluid density (liquid)Vbf = Volume of liquid displacedg = earth gravitational acceleration
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ARCHIMEDES’S LAW
Hal.: 10 ISI DENGAN JUDUL HALAMAN TERKAIT
The singking body
FA < w mf g < mb gVf ρf g < Vb ρb g ρf < ρb
Note:mb = mass of bodymf = transfered liquid massVb = volume of bodyVf = transfered liquid volumeρb = 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
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ARCHIMEDES’S LAW
Hal.: 11 ISI DENGAN JUDUL HALAMAN TERKAIT
The suspending body
FA = w mf g = mb gVf 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 bodymf = transfered liquid massVb = volume of bodyVf = transfered liquid volumeρb = the density of body ρf = the density of liquid
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ARCHIMEDES’S LAW
fb
fb ρVVρ =
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 gVf ρf g = Vb ρb g
because Vf < Vb then ρf > ρb
w
FA
water
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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.
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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
tension surface
===
γNote:
w2
w1
One layer of soap water
water
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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
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CAPILLARITY
hgρcosθ2γ=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)
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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
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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
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VISCOSITY OF FLUID AND STOKES LAW
Hal.: 19 ISI DENGAN JUDUL HALAMAN TERKAIT
( )fbT ρρη
grv −=
2
9
2
Note:
vT = terminal velocity (m/s)
η = viskositas fluida (Ns/m2)
ρb = dencity of body (kg/m3)
ρ f = dencity of fluid (kg/m3)
g = gravitational acceleration (m/s2)
r = radius of sphere (m)
AdaptifHal.: 20 ISI DENGAN JUDUL HALAMAN TERKAIT
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