The document describes a pre-lab activity on forces and motion. Students are asked to analyze three scenes where Joe is trying to push a file cabinet across the room. In the first scene, the cabinet does not move when Joe looks at it. In the second scene, the cabinet still does not move when Joe begins pushing. In the third scene, the cabinet begins to slide when Joe pushes it. Students are tasked with identifying the forces acting on the cabinet in each scene and explaining why it moves in the third scene but not the first two. They are also asked how the motion would change if the floor was icy.

1. Name____________________________________________
Grade____________________________________________
Forces and Motion Pre Lab
Joe needs to push a file cabinet across the room. He begins by just looking at it. (Scene 1)
He then begins pushing on the file cabinet. At first, the file cabinet does not move. (Scene 2) Then
the file cabinet begins to slide. (Scene 3)
Scene 1: Scene 2: Scene 3:
Joe not pushing Joe pushing but cabinet not Joe pushing and cabinet
moving moving
a. Use words and pictures to describe all the forces you think are acting on the cabinet in each
scene.
b. Why do you think the file cabinet moves (accelerates from zero) in scene 3 but not in scene 1
or 2?
Forces and Motion 1

2. c. If the floor is covered with ice, how would the motion of the cabinet change?
Forces and Motion 2

3. This page is blank
Forces and Motion 3

4. Name____________________________________________
Forces and Motion
Learning Objectives:
• Be able to identify when an object is being acted upon by unbalanced forces.
• Be able to predict the change in motion when a force is applied to an object.
Go to the PhET Website (just google PhET to get there). Go to the simulations, click on “physics” and find the “Forces in
1-Dimension” simulation (it may take a few moments to load).
Part 1: Understanding balanced and unbalanced forces
Open the Forces and Motion Simulation by clicking the icon on your computer’s screen.
1. What do you observe about applied force and motion?
2. What do you observe about friction force and motion?
3. Using the simulation for help, we drew pictures showing Joe and the file cabinet.
Draw the force vectors on the file cabinet in each scene. Label them Balanced or
unbalanced.
Scene 1: Scene 2: Scene 3:
Joe not pushing Joe pushing but cabinet not Joe pushing and cabinet moving
moving
4. What happens to the applied force when Joe stops pushing on the cabinet?
5. Can the object still move, once Joe stops pushing?
Forces and Motion 4

5. Part 2: Understanding Applied, Friction and Total Force
6. Apply enough force to move the cabinet.
a. What happens to the Friction Force when you stop applying force?
b. What happens to the Friction Force once the cabinet stops moving?
Part 3: Graphing
Click on , and to show the graphs of motion. To go back to the
main screen, you click the X in the right corner of the graph.
Remember…it is not the presence of forces that cause acceleration…it is the presence of unbalanced or
NET forces!
A. Set the “Initial Position” to -2 m. the simulation between runs to reset the simulation.
B. Have Joe push the cabinet until it begins to move, then have him stop pushing completely.
Draw a sketch of the velocity, and position graphs produced.
Velocity vs time Position vs time
Forces and Motion 5

6. Name____________________________________________
Grade____________________________________________
Forces and Motion Homework
1. Joe needs to push a file cabinet across the room. He begins by just looking at it. (Scene 1)
He then begins pushing on the file cabinet. At first, the file cabinet does not move. (Scene 2) Then the file
cabinet begins to slide. (Scene 3)
Scene 1: Scene 2: Scene 3:
Joe not pushing Joe pushing but cabinet not Joe pushing and cabinet
moving moving
a. Use words and pictures to describe all the forces you think are acting on the cabinet in each scene.
b. Why do you think the file cabinet moves in scene 3 but not in scene 1 or 2?
c. What do you think Joe could do to make the cabinet move faster?
Forces and Motion 6

7. d. If the floor is covered with ice, how would the motion of the cabinet change?
e. What would be different if Joe was moving a book, instead of a file cabinet.
2. How useful for your learning was this science activity, compared to other science class activities?
(circle)
More useful About the same Less useful
How enjoyable was this science class activity, compared to other science class activities? (circle)
More enjoyable About the same Less enjoyable
Why did you or did you not find it useful or enjoyable?
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Conclusion Questions:
1. As a small force was applied to the cabinet, the cabinet didn’t move because the magnitude of the force of
friction was larger than / smaller than / equal to the applied force. BE CAREFUL HERE
2. Our experiment showed that static (not moving) friction is greater than / less than kinetic (moving) friction.
3. I’m not accelerating, so the net (vertical) force on me, while I’m sitting here doing this lab is _________.
4. Without friction, applying a constant force produces a decreasing / constant / increasing acceleration.
5. Without friction, applying a constant force produces a decreasing / constant / increasing speed.
6. While coasting (no applied force) without friction, the acceleration is __________ and velocity is ________________.
14. Write 1.)Which direction you think the object is moving. 2.) Will it speed up or slow down. 3.) Why?
a.
b.
Forces and Motion 7

8. c.
Forces and Motion 8