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# Investigation 3 – Lab

### MINDSET

This Investigation is designed to:

• illustrate that an object in motion remains in motion unless an outside force acts on the object, and
• show you that planetary orbits are governed by the forward motion of planets and the gravitational pull of the Sun

### BE PREPARED

Student Preparation for the Investigation includes gathering the following materials.

Note: The materials are listed in your SDR. They are also listed below for your reference.

• (1) scooter
• (1) piece of rope

### INVESTIGATE

• A scientist named Sir Isaac Newton described the motion of objects in three statements called Newton’s Three Laws of Motion.
• During this investigation, you will investigate the First Law of Motion, which reads as follows:

• Reflect on the PreLab video as you move through the procedural steps.
• During the experiment, every procedural step is important. If one step is skipped, data can become invalid. To help you keep on track, read each step thoroughly, complete the step, then check it off (Read it – Do it – Check it).
• Complete all of the procedural steps in your SDR.

Note: The procedural steps are listed below for your reference.

Note: For Investigations Three and Four, you will need a substantial amount of space to perform the experiments. Each group of students will need an area approximately four meters by four meters. If possible, this space could be found in an unused gymnasium, auditorium, cafeteria, or other large room. If such a space is not available, a wide hallway would suffice. If even a wide hallways is unavailable, the lesson may have to be adapted as a class Investigation rather than small group activities.

Trial 1: Model the movement of the planets

1. Choose one student in your group to sit on the scooter (student #1) and one student to push the student on the scooter (student #2).
2. Student #1 – sit on the scooter so that no part of your body is touching the floor.
3. Student #2 – push the student sitting on the scooter. When pushing, push firmly, but carefully, on the middle of student #1’s lower back. Give one firm push and then release.
1. What acted upon the scooter to cause it to move from a state of rest?
1. After it was in motion, what was the movement of the scooter?
1. After it was in motion, why did the scooter come to a stop? Describe your answer in terms of Newton’s First Law of Motion.
1. Imagine that the scooter was put in motion and that no outside force acted on it to stop its motion. Draw the path of the scooter if no outside force acted on it.

Note: Switch roles with your group members to experience all aspects of the Investigation as time allows.

Trial 2: Model the forces that keep objects in orbit

• Just as the scooter had forward motion, so do the planets and the Moon. Each planet (including Earth) and the Moon are experiencing forward motion. Through performing the next two models, you will determine why the planets have an elliptical orbit around the Sun rather than traveling in a straight line past the Sun.
• Obtain the Student #1 and #2 Role pages. Read your paper to determine your role in the experiment.

Note: The Student #1 and #2 Role Page information is listed at the bottom of this page for reference.

Model A

1. The first model will require two students from your group to perform and the rest of your group to observe. First, read the directions, then perform the model.
2. All planets have a forward motion. Model the forward motion of the planets.

A. Student #1: Stand in the middle of your group’s work area.

B. Student #2: Walk in a straight line past Student #1. You should walk approximately 1 m from Student #1.

1. Record: Describe the movement of Student #2. Student #2 moved in a straight line past Student #1.
1. Next model the forward motion of the planets and the gravitational pull of the Sun. Follow the directions on the Role Pages from your teacher.
1. Record: Describe the movement of Student #2. Student #2 circled Student #1 as a result of the forward motion of Student #2 and the pull of Student #1.

Model B

1. Place the scooter at the starting position of Student #2 in Model A. Pick three students to perform Model B.
2. Model the forward motion of the planets. First, read the directions, then perform the model.

A. Student #1: Stand in the middle of your group’s work area.

B. Student #2: Sit on the scooter.

C. Student #3: Push the student who is sitting on the scooter, on the lower-middle of his or her back, in a straight line past Student #1.

1. Record: Describe the movement of Student #2. Student #2 moved in a straight line past Student #1.

A. Student #1: Loop the rope through the handle on the scooter. Hold both ends of the rope tightly so that the rope does not slide from your hands.

B. Student #2: Sit on the scooter.

C. Student #3: Attempt to push the student who is sitting on the scooter, in the middle of his/her lower back, in a straight line.

1. Record: Describe the movement of student #2 and why it occurred.
1. Refer to Model A and Model B. What did the models represent?

Note: Switch roles and experience both roles of the Investigation as time allows.

Student Role Resource Page

Student #1

Your task is to stand in the middle of your work area. When your partner walks toward you, reach out and grasp his or her wrist firmly but not aggressively. Your partner will continue walking, but you must not let go of his or her wrist. You also may not move from the center of your area. This will likely require that you turn in place as your partner walks. This will cause your partner to walk in a circle.

It is important that you act responsibly throughout this experiment. To properly model motion, you must act deliberately but carefully. Avoid moving suddenly so that you and your group remain safe. Have fun!

Student Role Resource Page

Student #2

Your task is to again walk in a straight line past your partner. However, this time your job may be more difficult. If your partner somehow keeps you from accomplishing your goal, simply try to maintain forward motion. Keep walking.

It is important that you act responsibly throughout this experiment. To properly model motion, you must act deliberately but carefully. Avoid moving suddenly so that you and your group remain safe. Have fun!

### CLEAN UP

Be sure to clean up and return the scooters and rope to the lab if necessary.