1. Pressure

2. Pressure Is the amount of force acting over a given are on an object.
Compression:
Is a decrease in volume produced by force.

3. What is compressible?
Gas?
Liquids?
Solids?

5. You are lying on your back enjoying the view of the nigh sky when your friend decides to come over and stand on your chest. Owe. It would be quite less painful if they decided to ‘steam roller’ you. Though they have the same weight in each scenario and thus exert the same force on you, the standing version exerts a greater pressure against you. Imagine the pressure if they were on their tip toes!

6. Deformation
Means a change of shape without being forced into a smaller volume.

7. Example

8. At the surface of earth we are under a tremendous amount of air and consequently we are under pressure. We are designed for this pressure and do not notice it. However, if you go up in altitude you can observe effects of the decrease in pressure.

10. Technically there is no such thing as ‘suck’ or ‘suction’
Technically there is no such thing as ‘suck’ or ‘suction’. Vacuums can not pull something up. All these types of things can do is remove air so that air pressure pushes things up. The same is true when you drink a milk shake or a carburetor receiving fuel. Since air pressure is a limited quantity it means that there is a limit on how high you (or anything) can “suck” water up a straw (or pipe). That limit is just over 10 meters. No matter how ‘strong’ the pump is, that is the limit because that is the ‘strength’ of the air pressure that is doing the pushing.

11. P =F/A
F/A(length * width)
For example a BMX rider and bike weight 1200N. They are on a rigid sheet of steel that is 1.0 m by 2.0 m. How much pressure does the sheet exert on the ground?

12. P=F/A
=1200N/(1.0 m * 2.0 m)
=1200N/2.0 m2
=600N/m2
=600 Pa

13. A car is exerting 3100N of force on a ramp of 6m by 7. 5m
A car is exerting 3100N of force on a ramp of 6m by 7.5m. What is the pressure exerted?
A person exerts 500Pa of pressure on a table of 1.5m by 0.5m. What was the force required?

14. Let try some questions: Get out a piece of paper to write answers on
Pg 296 Practice problems #1-3
Pg 299 # 4, 6