Presentation on theme: "Fluid Fluid - any substance that “flows”… liquids and gases."— Presentation transcript:
1 Fluid Fluid - any substance that “flows”… liquids and gases. Ex. Water and Air
2 Fluid Pressure Pressure - force per unit of area. A force that exist in fluids are caused by the mass and motion of the particles making up the fluid.
3 Calculate Fluid Pressure P = ρ · g · h Units: N/m2 or PaAir pressure at sea level is 14.7 psi = 760 mm Hg = 101 kPa = 1 atm.ρ of H2O is 1000 kg/m3
4 Calculate Fluid Pressure What is the pressure due to water 3.0 m below the surface of a lake?A truck falls through the “too thin” ice at Lake Poinsett, and sinks 7 m to the bottom.What is the pressure on the truck at this depth?If the area of one of the doors on the truck is 0.7 m2, calculate the force that the water exerts on it.
5 Properties of Pressure Fluid pressure acts in all directions.Force of gravity causes the pressures in a fluid to vary with depth only. Not with horizontal position.Fluids will move from areas of high pressure to areas of low pressure.
6 HydraulicsPascal’s Principle - pressure is transmitted equally throughout a confined liquid.Multiplies force!Ex. Brakes, hydraulic lifts, etc.
7 Calculate Hydraulics P = F1 = F2 The small piston of a hydraulic lift has a cross sectional area of 3 cm2, and the large piston has an area of 200 cm2. What force must be applied to the small piston to raise a load of 15,000 N?A1A2
8 BuoyancyThe upward force exerted by a fluid on a substance partly or completely immersed in it.Fb< wt. of sub. SINKFb ≥ wt. of sub. FLOAT!
9 Calculate Buoyant Force Weight Difference method~ Fb= Dry weight – Wet weightWeight of displaced water~ Fb= ρ · g · v
10 Archimedes PrincipleArchimedes Principle - The buoyant force acting in a substance in a fluid at rest is equal to the weight of the fluid displaced by the substance.Fb= weight of displaced fluidorFb= ρ · g · v
11 Sink or Float? Density (object)> Density (fluid) SINKS Density (object) ≤ Density (fluid) FLOATS
12 Bernoulli’s Principle For a fluid undergoing steady flow, the pressure is lower where the fluid is flowing faster.Ex. Shower curtain, airplane wing, etc.