Under Pressurehttp://

phet.colorado.edu/en/simulation/under-pressure by Trish Loeblein June 2012

modified by K Cook February 2013

Learning goals: Students will be able to 1. Investigate how pressure changes in air

and water.2. Discover how you can change pressure. 3. Predict pressure in a variety of situations

Directions: • Explore the simulation to find out how

pressure changes in air and water.• Discover how you can change pressure in the

simulation. • Go through the following slides as a guide and

answer the questions. – Make your guess – Use the sim to check your guess– Go to the next slide to see if you got it right

1. Order from lowest to highest pressure.

A. A<B<C B. C<B<A C. all are equal

answer

A. A<B<C

2. Look at the markers. A.Order from lowest to highest pressure. B. Why (think about F &SA)?

A. Y<Z<X B. Y<X<Z C. Z<X<Y D. X<Z<Y E. two are equal

X

Y

Z

answer

B. Y<X<ZY is less force because only air above (less F less P)Z is most because even though same depth as X, it has less surface area (less SA more P)

3. What will happen to the pressure if more water is added?Is this related to force or surface area?

A. increase B. decrease C. stay the same

answer

A. increase because there is more force

4. What will happen to the pressure if more water is added while the same amount is removed? Why?

A. increase B. decrease C. stay the same

answer

C. stay the same because force is the same

5. What will happen to the pressure if the fluid were changed to honey? Why?

A. increase B. decrease C. stay the same

answer

A. increase because more force

6. If a 250 kg mass was put on the water column, what will happen to the pressure? Why?

A. increase B. decrease C. stay the same

answer

A. increase because more mass leads to more force (there is more weight)

7. If the only change was to remove the air pressure , what will happen to the pressure? Why?

A. increase by 101.3 kPa B. decrease by 101.3 kPa C. stay the sameD. Something else

answer

B. decrease by 101.3 kPa(If no air, then less force)

8. If the only change was to go to a place where the gravity was doubled, what will happen to the pressure? Why?

A. Both pressures would doubleB. Only the air pressure would doubleC. The air pressure would double, and the

water pressure would increase someD. Something else

answerA. Both pressures would

double because increased gravity acting on the mass of air AND water is increasing the weight (force) of both

(more gravity more force more pressure

9. How do the pressures at the two locations compare? Why?

A. X>Y B. Y>X C. They are the same

X Y

answerC. They are the same because it’s the surface area of the entire body of water and they are part of the same body of water