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Force, Pressure and Area. The force acting on a certain area is called pressure If you change the area but keep the force the same the pressure changes Ex. Snowshoes, boxing gloves, thumbtack Pressure = Force (N) P = F = N/M 2 or Pascal (Pa) Area (m 2 ) A
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The force acting on a certain area is called pressure • If you change the area but keep the force the same the pressure changes • Ex. Snowshoes, boxing gloves, thumbtack Pressure = Force (N) P = F = N/M2 or Pascal (Pa) Area (m2) A Kilopascal (kPa) = 1000 Pa
Pascal’s Law • Pressure exerted on a contained fluid is transmitted undiminished in all directions throughout the fluid and perpendicular to the walls of the container • Ex. Squeezing anywhere on the tube of toothpaste will force toothpaste out of the tube • Remember liquids take the shape of their container and are practically uncompressible
Hydraulic Lift • A mechanical system that lifts heavy objects • Uses fluid under pressure in a closed system • Your circulatory system is a closed system • Has a small cylinder and a large cylinder, each filled with hydraulic fluid (usually oil) • Both cylinders have a platform or piston that rests on the surface of the fluid • A hydraulic lift uses a liquid to produce a large force on a load with a small effort force on the liquid
500N of force, small piston is 5cm2, large piston is 500cm2 Small piston: Pressure = F = 500 N = 100 N/cm2 A 5 cm2 Large piston Pressure = F = 500 N = 1 N/cm2 A 500 cm2