Chapter 14 Forces in Fluids

Fluid Pressures Like solids, liquids and gases can be forces (push or pull) Force that exists in fluids are caused by the mass and motion of the particles making up the fluid Therefore, fluid pressure is exerted equally in all directions Fluid particles are able to move more freely than solids & are constantly moving in all directions

To calculate pressure: Pressure = Force Area Units = Newtons/cm 2 Normal air pressure at sea level is N/cm 2 or approximately 15 pounds per square inch

higher Pressure in higher elevations is less. Why?? There are less air molecules the farther you move away from Earth’s surface due to less gravitational pull.

Differences in pressure affect us Tire Pressure Air Pressure Lung Pressure

Fluids move from an area of high pressure to low pressure 1.When you suck on a straw, you remove the air from the straw causing air pressure in the straw to DECREASE. 2.Normal air pressure is greater than the pressure in the straw & pushes down on the drink & forces it up the straw.

Fluids move from an area of high pressure to low pressure 1.A fan inside the vacuum cleaner forces air out, causing air pressure to decrease inside of the canister. 2.Air pressure outside the vacuum is greater and forces both air and dirt into the canister.

BREATHING

Fluids move from an area of high pressure to low pressure When you exhale, your diaphragm muscle moves up and reduces the size of your lungs. This increases the air pressure in the lungs so that its greater than the air pressure outside of your lungs. This forces air in a higher pressure area out of your lungs to the lower air pressure area outside of your body.