Chapter 1: Force and Velocity

Transcription

1 Chapter 1: Force and Velocity

2 FM: WARM-UP Students consider how diagrams use arrows and lines to represent force and velocity. (5 min) Signifying Changes in Motion Answer Here

3 FM: WARM-UP Students consider how diagrams use arrows and lines to represent force and velocity. (5 min) Signifying Changes in Motion Answer Here

4 FM: EXPLORING THE FORCE AND MOTION SIM Students explore the Sim to become familiar with its features. (10 min) What caused the pod to change direction? In the last lesson you used physical materials to identify five ways that an object s velocity can change. Today we will focus on what causes those changes in velocity that you observed in the previous lesson. Force and Motion Simulation. This digital simulation is a tool to help students understand and gather evidence about how the motion of objects can change.

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7 In Build: Drag objects with different masses onto the background. Select objects and change their initial velocity.

8 In Run: Objects can move in different directions. Exert small pushes in real time. Multiple taps create a stronger force. PREPARE FORCE allows time to plan the action. EXERT FORCE continues the action. Tails stretch out behind objects to show direction. Longer tails indicate greater velocity. Arrow length indicates how hard an object is pushed in a particular direction.

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11 In Analyze: Move the blue scrubber bar to the left to review the action. Numbers on arrows indicate the strength of the push. Use the data tables to determine the velocity or kinetic energy of objects at a specific time. Kinetic energy information is related to the velocity of an object, but is not a focus of this unit.

12 FM: EXPLORING THE FORCE AND MOTION SIM Students explore the Sim to become familiar with its features. (10 min) What caused the pod to change direction?

13 FM: GATHERING EVIDENCE ABOUT VELOCITY CHANGES Students use the Sim to determine how to cause an object s velocity to change in a specific way, then share the information with a small group. (25 min) START THE FORCE AND MOTION SIM HERE

14 Project the Force and Motion Simulation and model filling in the first row of the data table. Explain that you will start with an object that is not moving and see how you can make it start moving. In Build, drag an object onto the screen. Ask students what the initial velocity would be if the object is not moving. [Zero.] Point out the object s velocity is zero and go to Run. Ask students to suggest a way to make the object start moving. [Push it.] Press PREPARE FORCE, set up a force to exert on the object, and then press EXERT FORCE. Ask students if there are other ways they can make the object start moving. Press reset and exert different forces on the object in order to make it start moving. You can demonstrate the different directions a force can be exerted using the Force panel. You can also use another object to hit the object that is not moving. To make an object start moving, I can push it. If I make another object run into it, it will also start moving. This can happen in any direction. In Row 1 (start moving) of the data table, I would write, hit or push in any direction.

15 FM: GATHERING EVIDENCE ABOUT VELOCITY CHANGES Students use the Sim to determine how to cause an object s velocity to change in a specific way, then share the information with a small group. (25 min) You will share with your group what you learned about the velocity change you focused on. As each person in the group presents, the other group members will listen and record in their data tables what that person did to make this velocity change happen. Make sure each person has an opportunity to share what they learned in the time allotted. hit or push in any direction.

16 FM: GATHERING EVIDENCE ABOUT VELOCITY CHANGES Students use the Sim to determine how to cause an object s velocity to change in a specific way, then share the information with a small group. (25 min) What term do you think physicists use to describe a push or a pull? To cause each of the velocity changes, you had to exert a force. Any time an object changes its motion, a force must have been exerted on it.

17 FM: GATHERING EVIDENCE ABOUT VELOCITY CHANGES Students use the Sim to determine how to cause an object s velocity to change in a specific way, then share the information with a small group. (25 min) FIRST: Predict the direction a force must be exerted to cause each velocity change and share their predictions with your partners. NEXT: Work with their partners to test your predictions.

18 FM: GATHERING EVIDENCE ABOUT VELOCITY CHANGES Students use the Sim to determine how to cause an object s velocity to change in a specific way, then share the information with a small group. (25 min) Objects can start moving, stop moving, speed up, slow down, or change direction. If I exert a force on an object, the way the object changes velocity depends on the direction the force was exerted.

19 FM: GATHERING EVIDENCE ABOUT VELOCITY CHANGES Students use the Sim to determine how to cause an object s velocity to change in a specific way, then share the information with a small group. (25 min) In each case a force was exerted on the object, which caused it to change velocity. The specific effect the force had on the object s velocity was determined by the direction in which the force was exerted. cause: an event or process that leads to a result or change. effect: a result or change that happens because of an event or process.

20 FM: HOW THE POD CHANGED ITS VELOCITY Students determine the direction of force needed to cause a pod to stop. (5 min) QUESTION? The pod is moving at medium speed as it approaches the space station, and then it stops. In what direction would the thrusters need to exert a force (fire), in order to change the velocity of the pod so it stops moving?

21 FM: HOW THE POD CHANGED ITS VELOCITY Students determine the direction of force needed to cause a pod to stop. (5 min)

22 FM: HOMEWORK Students think about cause and effect as they categorize the forces that can cause changes in velocity. Identifying Cause and Effect