Objectives Fluids Pressure inside fluids Hydraulic Lift Buoyancy

Objectives: • • Fluids Pressure inside fluids Hydraulic Lift Buoyancy Force and Displaced Volume Bernoulli’s Principle

Pressure inside fluids Pressure = (density) (g) (height) Pressure depends ONLY on the depth (height of fluid on top) height Q 1. How much is the pressure inside the pool, 1 m below the water surface?

How do we measure pressure? Units: “Water seeks its own level” when the pressure on both sides is equal Pressure on LEFT side is greater Pressure on RIGHT side is greater

How do we measure pressure? Q 2. Which pressure is higher? (a) Gas (b) Atmospheric Pressure (c) Both are the same

Hydrostatic Pressure 20 P 1. While standing, your blood pressure is normally greatest in your (a) head (b) heart (c) feet (c) same in each P 2. The pressure in a liquid depends on liquid (a) density (b) depth (c) Both of these P 3. What is the mass of 1 cubic meter of water? (d) Neither Ans. P 4. Lobsters live on the bottom of the ocean, which means their density is (a) Greater than the density of sea water (b) Equal to the density of sea water (c) Less than the density of sea water

The Hydraulic Lift Pascal’s Principle: Force (in) Area (in) = Force (out) Area (out) Q 3. You apply a force of 100 N on a piston with an area of 1. 0 cm 2. What can you lift on the other side where the area of the platform is 4. 0 m 2?

The Hydraulic Lift 20 P 1. You apply a force of 100 N on a piston with an area of 1. 0 in 2. What force does the fluid exert on the other side where the area of the platform is 25 ft 2 Ans. P 2. In a hydraulic system a 20. 0 -N force is applied to the small piston with cross-sectional area of 25. 0 cm 2. An object with what mass can be lifted by the large piston with area 50. 0 cm 2. Ans. P 3*. Compressed air in a car lift applied a force to a piston with radius 5. 00 cm. This pressure is transmitted through a hydraulic system to a second piston with radius 15. 0 cm. How much force must the compressed air exert to lift a vehicle weighing 1. 33 x 104 N? Ans.

Displaced Volume An object submerged in fluid displaces volume that is equal to its own volume Example: A 784 -g object Displaces water as shown: Initial Water Level: 150 m. L Find the Volume of the object Object is submerged Water Level is now: 190 m. L Note: 1 m. L is the same as 1 cm 3 ( the same as cc) Find the density of the object Volume of the object is : 190 m. L – 150 m. L = 40 cc (cubic centimeters) Density: (784 g) / (40 cc) = 19. 6 g/cm 3

Bernoulli’s Principle Increase in speed occurs simultaneously with decrease in the pressure for a fluid flowing horizontally. Examples Airplane Wing: Wings are designed So that air above them moves faster Than the air below the wing. The pressure at the bottom is then Larger than the pressure on top – Lift Force Cars at intersection: As you wait for a left turn, whenever A car that goes straight passes you, you feel a pull towards The car