Chapter 7Mr. Jackson Nov. 22, 2010

PressureFluids and Air have pressure The amount of force exerted over a given

area is pressurePressure is calculated as force/areaThe SI unit for pressure is the Pascal

Fluids exert pressure evenly in all directionsIn Cornell note system what is this

phenomenon know as?

The gases are held in place by atmospheric pressure

The higher you go the thinner the air becomes and therefore the harder it is to breathe.

Depth and PressureAs you go deeper into the ocean pressure

becomes higher

Allowing us to BreatheThe pressure differential between the outside

air and in your lungs allows you to bring in air.

Tornados Tornados are very low pressureThis causes objects to rush into the storm.

Buoyant ForceThe upward force that fluid exerts on all

matter

What allows objects to FloatIf an objects density is less than that of the

liquid it is in it will floatIf it is the same it will suspendIf it is higher it will sink

BoatsBoats have a really high density so they

change their shape to allow more area of the boat to be in contact with the water

This will allow the boat to float

SubmarinesSubmarines add water to ballast tanks to

change its mass and to sink lower into the water.

Fish use a similar method but they fill a swim bladder with air to rise in the water

Bernoulli’s PrincipleAs the speed of a moving fluid increases the

fluids pressure decreases.This allows the wings of an airplane to create

Lift.

Factors that Affect FlightLiftThrust- the forward motion created by

enginesWing SizeDrag- the force opposing motionIrregular Drag is know as turbulence

Pascal’s PrincipleHydraulic devices use this principleWhen the pressure of the fluid changes it

expands equally in all directionsHydraulic devices multiply force many times.Brakes are the biggest example of hydraulics.