1. Pressure
Section 6.1

2. What is pressure? It’s related to the word press Go ahead…
press your finger on your hand
press harder
press lighter
You are changing the amount of force
Pressure refers to a force pushing on a surface

3. Calculating Pressure Pressure = Force / Area
Area of a rectangle = base x width
Pressure is measured in Pascals
Force is measured in Newtons
Area is measured in m2 or cm2
The larger the area of contact, the smaller the pressure
The smaller the area of contact, the larger the pressure

4. Try it!
If you poke your hand with your opposite thumb with 12N of force. Your thumb is roughly 1 cm by 1 cm. Calculate the pressure that you are exerting.
Now, press your thumb nail into your hand with the same force as before. Which hurt more, your thumb or your thumb nail? Explain why!

5. Try It!
Create a solve for A
Create a solver for F

6. Fluid Pressure Fluid – a substance that can easily flow
can change shape.
Solids cannot be fluids. Liquids and gases can.
In fluids, molecules are constantly moving in all directions
All of the forces exerted by the individual molecules in a fluid add together to make up the pressure exerted by the fluid.

7. Why does the atmosphere exert pressure on you?
The atmosphere is gas
Gas is a fluid
Fluids exert pressure
So, the atmosphere exerts a pressure on you

8. Balanced Pressure
If the atmosphere is exerting pressure on me, why don’t I feel it like I did when I pressed on my palm with my thumb???
In a fluid that is not moving, pressure at a given point if exerting equally in all directions.
Air is pushing on the palm of your hand at N/cm2 it is also pushing on the back of your hand at N/cm2
Pressure inside of your body balances pressure outside of your body

9. Variation in Fluid Pressure
Have your ears ever popped in a plane?
Air pressure decreases as elevation increases
The higher you go, the less the pressure
Have you ever dove too deep and your ears hurt?
Water pressure decreases as depth increases
The deeper you go, the higher the pressure