GEARS 2

INTRODUCTION

Gears aren't always the same size and don't always have the same number of teeth. Let's investigate what happens with different sized gears.

MATERIALS

1 set of gears
1 ruler

PROCEDURE

1. For this part of the experiment, we are going to use a small gear as the follower and a medium gear as the driver. Set them up on the base board with the marked teeth touching.

2. Turn the driver one time and record how many times the follower turns.

3. Next turn the driver 2 times and then 3 times and record how many times the follower turns.

NUMBER OF TURNS
DRIVER NUMBER OF TURNS
FOLLOWER
1
2
3
5

4. Graph your results on the next page.

5. Use the ruler to draw a straight line through the points on your graph. The line should continue to the edges of the graph.

6. Use the graph to predict how many times the follower will turn if the driver turns 5 times: ________

7. Try it and record your results.

8. You were probably able to predict very accurately how many times the follower would turn. Let's see if it has anything to do with the number of teeth. Start by counting the number of teeth on a gear of each size and record it below.

9. Use the same set up as before: a medium gear for the driver and a small gear for the follower. Turn the driver one time and record how many times the follower turns.

DRIVER FOLLOWER
SIZE NUMBER OF TEETH NUMBER OF TEETH TURNS
Large 20
Medium 20
Small 20

DRIVER	FOLLOWER
SIZE	NUMBER OF TEETH	NUMBER OF TEETH	TURNS
Large		20
Medium		20
Small		20

10. Repeat step 9 using a large size gear as the driver.

11. Finally, repeat step 9 using a small gear as the driver.

DEDUCTION

Can you detect a rule or pattern in your data that will help you predict how other combinations of gears will work?

______________________________________________________

APPLICATION

Try using your rule: if the driver is a small gear ( ___ teeth) and the follower is a large gear ( ___ teeth), how many times will the follower turn if you turn the driver three times? ________

Now try it and see what happens: ________