1. Chapter 3, Section 1 Pressure
Forces in Fluids
Chapter 3, Section 1
Pressure

2. What is pressure?
It is a force exerted over an area on the surface of an object.
Gravity pulls you down with a force equal to your weight.
Your feet then exert a force on the surface of the earth over an area the size of your feet.

3. Pressure and Area
Pressure decreases as the amount of area covered increases
The greater the area being covered, the less the pressure on a given spot of that area.
Ex. – Boots vs. Snowshoes

4. Calculating Pressure Pressure = Force/Area (P=F/A)
Pressure is the force exerted on the surface of an object divided by the total area.
Force is measured in Newtons (N)
Area is measured in square meters (m2)
Pressure is labeled N/m2

5. Fluid Pressure A fluid is a material that can easily flow.
Fluid can change shape depending upon the container.
Particles (atoms) in a fluid constantly move in all directions.
Fluid pressure is the total force exerted by the fluid divided by the area over which the force is exerted.

6. Air exerts pressure because it has mass.
Air presses down on everything on Earth.
Balanced Pressure
Pressure at a given point is given equally in all directions.
The weight of the atmosphere (air) is pressing on you in all directions – the pressures balance each other out.

7. Variations in Fluid Pressure
As your elevation increases, atmospheric pressure decreases
Can cause your ears to pop
Going up in a plane
Going deep under water
The pressure becomes greater the further under water you go.

8. Measuring Pressure Barometer – used to measure atmospheric pressure
Decreasing atmospheric pressure usually means a storm is coming.
Increasing atmospheric pressure usually means fair weather