Unit 2 Notes: Pressure

(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

(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

(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

(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:

(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:

(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: