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Student Worksheet
Forces and Motion: Learning Activity Packet – Level I
An online lab that incorporates data collection, data analysis, graphing and differentiated instruction.
S8P3. Students will investigate relationship between force, mass, and the motion of objects.
b. Demonstrate the effect of balanced and unbalanced forces on an object in terms of gravity, inertia, and friction. (DOK 2)
Name(s): ______Section: ______
______Date: ______
PART I – Minimum Difficulty
Discussion: With your lab partner, discuss how you would define force. Record your definition of force in the space below.
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Lab Instructions:
1. Click on the following link or copy/paste it in your browser.
http://phet.colorado.edu/en/simulation/forces-and-motion-basics
2. Run the program titled Forces and Motion: Basics
3. Select the Tug of War tab and begin.
Figure-1
Observation and Analysis:
Set up your tug of war competition like the one seen in figure-1.
4. What do the brown arrows represent? ______.
5. Is one arrow larger than the other in this scenario? Why? ______.
6. Are they pointing in the same or different directions? ______.
7. Is the force balanced or unbalanced? Use the Claim, Evidence, and Reasoning (CER) format to answer this question. ______
8. Go to the menu screen and click the box titled “Values”.
Describe what happened when you clicked the box.
______.
9. What is the value of: Left Force ______Right Force ______
10. Click the green “Go!” button and write down what you observe in the space below the picture.
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11. Click the “return” button and move the blue figure so that it is positioned closer to the cart. Leave the red figure at the end of the rope. Did moving the blue figure cause a change in any of the forces acting toward the left? Explain your reasoning.______
12. Click the box titled “Sum of Forces”. What are the “sum of forces” acting on the cart?
______
Figure-2
13. Now add another blue figure to the left side of the cart.
How did the addition of another blue figure effect the
size of the “Left Force” acting on the cart? What amount
of force is on the “blue side” now? What is the
sum of forces acting on the cart?
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14. Discuss with your lab partner why you think subtraction was used to calculate the sum of the forces in the examples we’ve seen thus far? Record your reasoning below.
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15. Make a claim about what will happen when you click the green “Go!” button on Figure-2. Set up a simulation like that seen in Figure-2. Click the “Go!” button and describe what you observe. Did your evidence match your initial claim? Did the cart move in the direction of the greater force? Which direction has the most inertia? Why?
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Use the simulation to complete the table below:
Left Force(N) / Right Force
(N) / Sum of Forces
(N) / Direction of cart movement once “GO!” is pressed.
Summary:
16. During the simulation, when the sum of forces acting on the cart equaled zero, did the cart move?
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17. When the cart moved, were the forces acting upon it balanced or unbalanced? Explain your reasoning.
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18. When the cart moved, did it always move in the direction of the “sum of forces”?
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PART II – Motion
1. Click the tab “motion.”
2. Check the boxes next to “force, values, masses, and speed.”
3. Click the pause button.
4. Place a box on the skateboard. Type 200 in the box next to the word Newtons. See below.
5. Press the play button. Count to ten, what happens? ( look at the speedometer)
6. Repeat steps 4 and 5 with the refrigerator. (look at the speedometer)
7. Click the “Reset All” button.
8. Repeat steps 2-4 using different objects and different applied forces. You can also use people.
9. What happens to the speed? Does it slow down as different objects are added and the applied force is different?
10. What is your reasoning as to why this happens? Remember what INERTIA is!!!!!!!!!!!
11. How much time does it take for 1 crate, 2 crates, a refrigerator, the man, the girl, and the mystery object, with the same applied force get to maximum speed? Maximum speed is reached when the hand on the speedometer cannot go any further. (Record your evidence in the table below.) For the next part, you will need a timer. You may use a handheld stopwatch/phone, OR, for an online timer, open a new browser (Command N) and google ”online stopwatch,” or type in this url address: http://www.online-stopwatch.com/full-screen-stopwatch/
12. Complete the table. Fill in the missing values.
Object / Mass / Applied Force(Newtons) / Time (Use Stopwatch)
1. Crate / 300N
2. Crates / 300N
3. Refrigerator / 300N
4. Man / 300N
5. Girl / 300N
6. Mystery Object / 300N
13. Do you think the object’s mass determines how long it will take for that object to reach maximum speed with an applied force of 300N? Make a claim, provide your evidence, and explain your reasoning.
14. What approximate mass do you think the mystery box has based on how long it took to reach maximum speed at 3ooN?
Part III – Friction
1. Click the tab “Friction.”
2. Check the boxes next to “forces and speed.”
3. Place the refrigerator on the screen. Type 500 in the box by the word Newtons. See below:
4. What happened? Make a claim. Did the refrigerator move? Provide your evidence.
5. Click the “Reset All” button.
6. Check the boxes next to “values and speed.”
7. Place the refrigerator on the screen. Type 500 in the box next to the word Newtons. Slide the friction tab toward “None.”
8. What happens as you slide the friction tab closer to “None?”
9. Click “Reset All.”
10. Check the boxes next to “values and speed.”
11. Place any object on the screen. You can also place people on the screen.
12. Type 500 in the box next to the word Newtons. Slide the friction tab toward “None” or “Lots.” Stop the friction tab where the friction force arrow is between 100N and 200N.
13. Complete the table. Fill in the missing values.
Object / Applied Force (N) / Friction Force (N) / Sum of Forces (N)Crate / 200 / 125
Man / 472 / 272
Refrigerator / 51 / 99
Girl / 363 / 100
Garbage Can / 500 / 375
* You can use the Friction Tab to help you check your answers.
Come up with a formula we can use to find the sum of the forces (or Fnet).
Here are a few examples: Fnet = Fapplied – Ffriction or Fnet = Fapplied + Ffriction Write your answers below:
14. Calculate the Sum of Forces using the formula you came up with.
15. Click the “Sum of Forces” box. Did you get the same number using the formula you came up with?
Lab written and designed by Stephen N. Clontz, M. Ed
Modified by Christopher Holmes for BCSD