1. Unit 2 Notes: Pressure

2. (1) Particles & Motion All particles move.
Their speed and amount of movement depends on how much energy they have.
More energy = More movement + Faster Less energy = Less movement + Slower

3. (2) Pressure: The number of particle collisions against a surface.
More collisions = Higher pressure Fewer collisions = Lower pressure
You can change pressure by:
Changing the # of particles
Changing the energy of the particles
Changing the amount of space the particles have to move around in

4. (3) Drawing Pictures:
When we draw a picture or “model” to show the results of pressure, they always include:
Particles
2 Sides
Some sort of barrier / surface
The direction the barrier / surface moves
Anything that changes with the particles

5. (4) Example #1: Pop Bottle
We pour boiling hot water into a pop bottle. We cap it as fast as we can and leave it. Suddenly the sides of the pop bottle start to crush in on itself. Draw a picture / model below to show what happened:

6. (5) Example #2: Soap Bottle
We dunked the top of a water bottle in soap to form a film on top. We then place the bottom of the bottle into hot water. A bubble starts to expand out of the bottle into the air. Draw a picture / model below to show what happened:

7. (6) Example #3: Soap Bottle
We dunked the top of a water bottle in soap to form a film on top. We then place the bottom of the bottle into cold water. A bubble starts to expand down into the inside of the bottle. Draw a picture / model below to show what happened: