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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 moving |Joe pushing and cabinet moving |

|[pic] |[pic] |[pic] |

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. If the floor is covered with ice, how would the motion of the cabinet change?

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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 “motion” and find the “Forces in 1-Dimension” simulation (it may take a few moments to load).

Part 1: Understanding balanced and unbalanced forces

1. Open the Forces and Motion Simulation by clicking the icon on your computer’s screen.

2. Play with the first tab of the sim for about 5 minutes. What do you observe about force and motion?

3. Using the simulation for help, we drew pictures showing Joe and the file cabinet.

You should draw the force vectors on the file cabinet.

|Scene 1: |Scene 2: |Scene 3: |

|Joe not pushing |Joe pushing but cabinet not moving |Joe pushing and cabinet moving |

|[pic] |[pic] |[pic] |

4. Describe what is necessary to start the file cabinet moving.

5. Compare the Applied Force and the Friction Force.

a. What is similar?

b. What is different?

6. Use your answers to #5 to say whether the forces are balanced or unbalanced in each scene in question #3.

7. When the forces are balanced can the cabinet move?

Part 2: Understanding Applied, Friction and Total Force

8. How can you make the Friction Force vector longer?

9. 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?

10. Have Joe move a new object. How is moving this object different from moving the file cabinet?

11. Can you find 3 different ways to make the Total Force vector change?

List them here:

12. In your own words, what is Total Force?

13. For each case, draw the Total Force vector. Write which direction you think the object is moving and whether it will speed up or slow down.

a. [pic]

b. [pic]

c.

Part 3: Understanding Force and Change in Speed

14.

a. Give the sleepy dog [pic] a little push...

[pic]

...how much does the dog’s speed change?

b. Give the sleepy dog a big push...

[pic]

...how much does the dogs speed change?

15. Using your answers to Question #15, what general statement can you make about the relationship between the applied force and how fast an object changes its speed.

Part 4: Force and mass

Restore the default settings and turn off friction!!! For this part of the activity we will not be considering friction.

16. If you apply the same force to objects of different masses, what do you observe (provide specific data that you obtain from the graphs in the simulation)?

|Object |Mass (kg) |Applied Force (N) |Acceleration (m/s2) |

| | | | |

| | | | |

| | | | |

| | | | |

| | | | |

17. Describe the motion of an object while a constant force is applied using physics terms! Be sure to discuss the object’s velocity and acceleration.

18. If an object is given a push, and then the force is removed, describe the motion of the object using physics terms! Be sure to discuss the object’s velocity and acceleration.

19. What do you have to do to get the filing cabinet and the book to accelerate at the same rate? Take data and provide examples.

20. Using your observations and data from questions 1-4, determine a mathematical relationship between Force, Mass and Acceleration. Show all your work! Be sure to analyze your solution and explain why it makes sense! In addition, test it with the simulation to verify your solution and show evidence of your tests!

Name____________________________________________

Grade____________________________________________

Forces and Motion Post Lab

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 moving |Joe pushing and cabinet moving |

|[pic] |[pic] |[pic] |

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?

d. If the floor is covered with ice, how would the motion of the cabinet change?

[pic]

e. What would be different if Joe was moving a book, instead of a file cabinet.

[pic]

1. 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)

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Why did you or did you not find it useful or enjoyable? ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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