Action and reaction

1. Cut two rubber bands and tie them together to make a bungee cord about 30 cm long.

2. Team up so that each group has two Force probes. Attach one end of the bungee to one Force probe, and the other end to the other Force probe. Use the small eyebolt to attach the rubber bands.

3. Connect each Force probe to its own handheld computer. Refer to Technical Hints to see how to connect the cables.

4. Each team member will pull on one of the Force probes, much like a tug-of-war. When do you think the two force graphs will be the same, and when will they be different? Record your prediction in Notes on the handheld computer.

5. Start the software for each Force probe.

6. Set the force probe to zero. Refer to Technical Hints to see how to set the Force probe to zero.

7. Start recording. Vary the amount of pulling, who pulls first, and who doesn't move.

8. Save your data to the handheld computer.

9. Compare the graphs from the two force probes. What can you conclude? Was your prediction correct? Record your thoughts in Notes on your handheld computer.