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

Adaptif

area

forcepressure =

A

Fp =


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

Adaptif

HYDROSTATIC PRESSURE

h g p ρ=


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

Adaptif

HYDROSTATIC PRESSURE


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

Adaptif

FUNDAMENTAL LAW OF HYDROSTATIC


Source: http://superphysics.netfirms.com/t240754a.jpg

Every point located on a plane in a liquid have the same hydrostatic pressure

http://superphysics.netfirms.com/t240754a.jpg

Adaptif

FUNDAMENTAL LAW OF HYDROSTATIC


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

Adaptif

PASCAL’S LAW


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

http://home.wxs.nl/~brink494/hydr.htg/pascal.gif

Adaptif

ARCHIMEDES’S LAW


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

Adaptif

ARCHIMEDES’S LAW


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

Adaptif

ARCHIMEDES’S LAW


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

Adaptif

ARCHIMEDES’S LAW

fb

fb ρVVρ =


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

Adaptif

SURFACE TENSION OF LIQUID


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.

Adaptif

F=γ


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

Adaptif

CAPILLARITY


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

Adaptif

CAPILLARITY

hgρcosθ2γ=h


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)

Adaptif

VISCOSITY OF FLUID AND STOKES LAW


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

Adaptif



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

Adaptif



( )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

TERIMA KASIH

statis fluid

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