Learning Goals:



Name ___________________________________ Date ___________________ Per _______

Lab: pHet - Ramp Forces and Motion

Directions: Answer the following questions

I. Set up the following.

• Choose the introduction tab.

• On the right, choose free body diagram, friction (wood), force vectors, brick walls.

• On the bottom, choose crate .

II. Draw a free-body diagram of the person pushing the crate up the ramp below.

III. Choose the friction tab.

A. What direction is the friction vector?____________________________

B. What happens when you increase the static friction?________________________

C. What happens when you increase the kinetic friction?_________________________

D. What is the relationship between mass and friction? ________________________

IV. Choose the force graph tab.

E. When is the applied force negative? ________________________ __________________

F. On the right hand side change the friction to ice (no friction). Nudge the crate just a little and notice what happens. Why is there no net force (Fnet ) even though the crate is still moving?______________

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Learning Goal: Students will be able to calculate the net force on an object on an incline

1. Joe is moving his refrigerator to take to college and he begins by pushing it across the wooden kitchen floor.

On a flat surface like the floor, how do you calculate how hard he needs to push? Draw a free body diagram to help explain your answer and use the simulation Ramp: Force and Motion to check your ideas. Record the minimum force Joe would have to use to move the refrigerator on the kitchen floor.

[pic]

2. Later, Joe is ready to load his refrigerator onto the moving truck.

a. Explain how he would calculate how much force to use to lift the refrigerator straight up into a truck with no ramp.

b. Joe starts thinking about easier ways to get it in the truck and remembers he has some wood that he could use to make a ramp. How could he calculate the minimum force needed to push it up the ramp?

[pic]

c. Use the simulation to check your ideas by running experiments with different objects at several angles. Make a data table including several trials with the calculations. (see attached half sheet)

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