Fluid Statics
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Transcript of Fluid Statics
Fluid StaticsFluid Statics
Why do your ears hurt when Why do your ears hurt when you dive deep into a pool, and you dive deep into a pool, and how can steel float on water?how can steel float on water?
Fluid statics: pressure Fluid statics: pressure and densityand density
Pressure is Force/Area (N/mPressure is Force/Area (N/m22 = Pascals) = Pascals) A thumb tack is a good way to feel the A thumb tack is a good way to feel the
difference between Force and pressure.difference between Force and pressure. The atmosphere has a constant nominal The atmosphere has a constant nominal
pressure of 1.01 x 10pressure of 1.01 x 1055 Pa (or 1 atm) Pa (or 1 atm)
Fluid Statics: Pressure Fluid Statics: Pressure and Densityand Density
Density Density ρρ = mass/volume = mass/volume ρρ(water) = 1000 kg/m(water) = 1000 kg/m33
ρρ(aluminum) = 2700 kg/m(aluminum) = 2700 kg/m33
ρρ(gold) = 19300 kg/m(gold) = 19300 kg/m33
Fluid Statics: change in Fluid Statics: change in pressure with increased pressure with increased depthdepth
The deeper you dive into a pool the greater the The deeper you dive into a pool the greater the pressure is.pressure is.
Increased pressure PIncreased pressure Pgauge gauge = = ρρgh = pressure gh = pressure due to the weight of the fluid at a given depth due to the weight of the fluid at a given depth h.h.
The gauge pressure is the amount of increase The gauge pressure is the amount of increase in pressure compared to the surface (typically in pressure compared to the surface (typically the surface pressure is atmosphere)the surface pressure is atmosphere)
Hydrostatic pressure
Pressure in a fluid PPgauge gauge = = ρρghgh P=Pgauge + Psurface P=Pgauge + Psurface ( Psurface= Patm)( Psurface= Patm)
Fluid Pressure increase Fluid Pressure increase with depthwith depth
The total pressure at a given depth is The total pressure at a given depth is P=Pgauge + Psurface (where Psurface P=Pgauge + Psurface (where Psurface usually means Patm)usually means Patm)
Fluid pressure depends on depth and not Fluid pressure depends on depth and not on the shape of the container. on the shape of the container.
Buoyant Forces and Buoyant Forces and Archimedes Principle (280 Archimedes Principle (280 B.C. Greek scientist)B.C. Greek scientist)
The buoyant Force pushing up by a fluid The buoyant Force pushing up by a fluid = weight of the fluid displaced= weight of the fluid displaced
To calculate the weight of the fluid To calculate the weight of the fluid multiply the fluid density (multiply the fluid density (ρρ) by the ) by the displaced Volume and by gdisplaced Volume and by g
FFbuoyantbuoyant = = ρρVg = weight of the fluidVg = weight of the fluid