Circular Motion

Use the Snowball Protocol to ask and discuss: Describe a time when you saw an object move in a circular motion. What made it move that way?

1. Students begin in pairs, responding to a discussion question only with a single partner.
2. After each person has had a chance to share their ideas, the pair joins another pair, creating a group of four.
3. Pairs share their ideas with the pair they just joined.
4. Groups of four join together to form groups of eight, and so on, until the whole class is joined up in one large discussion.

Have students record their thinking in their student guides and finish before the experiment section.

Take a plate with a rim and put one of the balls on the plate. Give the ball a little push and observe the trajectory of the movement.

Think about what forces are causing the movement — you can prompt students to think about the contact of the ball with the plate and how it differs from the force of the air in contact with the piece of falling paper from activity one.

Think about what the direction of movement is, the direction of the velocity, and how that connects with the direction of the force. Have students share ideas.

Use a second plate and make a cut out on the rim of the plate. Repeat the steps from before: give the ball a little push and observe its movement.

In the student’s guide we have asked the students to design their own experiment to test what variables affect a pendulum’s swing. The idea is to encourage them to be creative, to understand how to design experiments, and to think like scientists and engineers. They are given a set of materials that they can use to do their experiments. This is to prompt them, but they should be allowed to use other materials in their design. As the teacher, you can ask prompting questions to get them to think about the different aspects of the experiments. We have included instructions for how to set up the experiment with the just materials included in the kit.

In the student guide, they will analyze their results and compare it to their hypotheses.

Continue to listen in on each groups' discussion, answer as few questions as possible. Even if a group is off a little, they will have a chance to work out these stuck points later.

What happened to the ball when it got to the cut out. Describe the forces acting on the ball.

Use the Turn & Talk Protocol to ask and discuss: If you swing a yo-yo or other object in a circular motion and then let go, which direction would the object fly?

1. Pair students up
2. Give them a minute to think quietly
3. Give students 2 minutes to discuss their thinking
4. Have students record their answers or share out to the whole group

Have students record their thinking by drawing or writing in their Student’s Guide.

Take the string and attach it to the whiffle ball. Make sure the string is tight so that the whiffle ball will not fly off.

Spin the string with the wiffleball attached. Try spinning it in the horizontal and vertical directions. Ask the students to predict where the wiffleball will fly off if they let the string go and if the direction will change depending on the position of the hand/wiffleball when they let the string go.

Do several tests of letting the string go when you are spinning the string vertically and horizontally. While still maintaining circular motion, you’ll want to spin the wiffleball as slowly as possible so that your group can actually determine the proper release point. Let the string go at different positions, for example when spinning up or down, or when it is farthest from you when spinning horizontally.

Make sure students are put into intentional groups. See above.

Students will complete the experiment using the Student Guide where we have outlined the experiment for students and along the way, they record results and answer questions.

Have students predict what patterns they think they will see when the laser shines through the different pieces of cloth.

(Optional) Have students look at the different swatches of cloth through the microscope and draw the patterns that they see into their notebooks. If you don’t have access to microscopes, try magnifying glasses, or just have students hold the swatches up to a light.

In the student guide, they will begin calculating the wavelength of a laser.

Continue to listen in on each group’s discussion, answer as few questions as possible. Even if a group is off a little, they will have a chance to work out these stuck points later.

Use the Concentric Circles Protocol to ask and discuss: Can you draw some conclusions from the two experiments about what direction the force and the velocity are for an object going in a circle?

1. Students form two circles, one inside circle and one outside circle.
2. Each student on the inside is paired with a student on the outside; they face each other.
3. The teacher poses a question to the whole group and pairs discuss their responses with each other.
4. Then the teacher signals students to rotate: Students on the outside circle move one space to the right so they are standing in front of a new person (or sitting, as they are in the video).
5. Now the teacher poses a new question, and the process is repeated.