SCIENCE 111: Forces and Motion. All Questions Answered.

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SCIENCE 111: Forces and Motion Which way do you think the cart will move in each of the pictures below? Explain your predictions using drawings and words. Trial Predict which way the cart will m... ove, LEFT or RIGHT. Explain your prediction Left The person on the lef t that is pulling the cart is bigger so it will go to the left. Right the person on the right that is pulling the cart is bigger so the cart will go right. Left The person on the lef t that is pulling the cart is bigger so the cart will go left It wouldn’t move It would not move because both the people are the same size and they are standing equally between the cart. Left They are the same size but the person on the lef t is closer to the cart so the cart will go left. 1. Go to PhET Force and Motion Basics and click “Net Force” to test your predictions using a series of trials. 2. Compare the predictions that you made in the table above to what happens to the cart of candy in each trial. If your prediction was correct highlight it in orange, if it was wrong highlight it in purple. 3. Try more trials using different combinations of people from the red and blue teams and try to find some “rules” that you can use to make predictions about which way the cart will move. a. Does a large person always win each competition? Provide evidence to support your answer. b. Do two people pulling on opposite sides always make the cart stay still? Provide evidence to support your answer. c. Does it matter what part of the rope a person holds? Provide evidence to support your answer. d. How does the “Sum of Forces” help you? Use the PhET Force and Motion Basics – “Motion“ screen to explore the impact of mass on the speed of a pushed object, such as a refrigerator, crate, or person: 1. What happens to the speed of the crate when you use the person to push it? 2. What is different about how the speed changes if the person pushes more? 3. What do you notice if the person pushes against the crate, opposite to the direction that the crate is moving? 4. Compare pushing one crate to pushing two crates. What differences and similarities do you notice about how the speed changes? Similarities— Differences— Name Learning Objectives: Students will be able to ● Predict how forces can change motion. ● Provide reasoning and evidence to explain motion changing or not. 1. Open the Forces and Motion Basics simulation and play with the Friction screen for a few minutes. a. How does the Friction screen differ from the Net Force and Motion screens? b. Also, what is something new you discovered? 2. Imagine that your friend, Sam is trying to move a box. a. Using what you learned by exploring, try drawing arrows to predict what might happen in the pictures below. (Try this part without using the simulation.) Sam not pushing Sam pushing but box not moving Sam pushing and box moving b. Check your sketches using the sim and make corrections if needed. List any new ideas you discovered. c. What do you notice about the similarities and differences between the Applied Force arrow and the Friction Force arrows in each situation? 3. How can you make the Friction Force more? What shows you that the force is more? 4. In your own words, a. describe Friction Force. b. describe Applied Force. 5. Have Sam try to move the refrigerator. What’s different from pushing the box? a. In the table, draw the Sum of Forces arrow for the different cases: Sam not pushing Sam pushing but refrigerator not moving Sam pushing and refrigerator moving SUM OF FORCES: 0 SUM OF FORCES: 0 SUM OF FORCES: 0 b. Were you able to move the refrigerator? If not, what would you have to change? Describe what you did. 6. Try pushing other things; you can even stack them. What have you discovered? 7. Can you find different ways to make the Sum of Forces arrow change? a. List at least three: b. In your own words, what is Net Force? 8. What are some ways you can change the speed? 9. Using your answers to Question #8, what general statement can you make about the relationship between net force and how fast an object changes its speed. [Show More]

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