PHYS 1405 – Conceptual Physics I

Galileo’s Hot Wheels

Leader: _________________________ Recorder: __________________________

Skeptic: _________________________ Encourager: ________________________

Materials

Hot Wheels sets

2 x ring Stands with clamps

Meter stick

Introduction

While awaiting trial for the publication of his book supporting the heliocentric model of the solar system, Galileo turned his attention to the study of motion. He studied motion by rolling balls down planes and making clever measurements of the time it took the balls to roll down the planes. (Stop watches wouldn’t be invented for centuries.) In this activity we will conduct one of Galileo’s experiments using Hot Wheels ^TM instead of a ramp and ball.

Procedure

1. Set-up

Attach the clamp to one of the ring stands so that the top is about 50 cm above the table. Attach a medium length of track to a long length of track, and then attach one end to the clamp and the other to the loop-the-loop base. Attach another long piece of the track to the other side of the loop-the loop base, and then finally attach another long length of track to the end. Position the ring stand and drape the last piece of length over the clamp on the second ring stand so that the angle it makes is the same as that of the other section of track.

2. Acquire Data

We will release the car from the side that is attached to the clamp. Use the meter stick to measure the height above the table from which the car is released. You should measure the height to the nearest millimeter (mm). When you record any measurement you should include the unit with which it was measured.

Height of release point: ____________________

Release the car and observe the maximum point to which it rises on the end ramp. Use the meter stick to measure the height above the table and the length along the track from the loop-the-loop base that the car traveled on the end ramp. Record your data in the data table in the row for trial 1.

Data Table

Trial	Ending Height above Table	Ending Length along Track
1
2
3
4
5

Move the ring stand supporting the end ramp back three or four inches. Release the car from the same starting position. Observe the maximum point to which the car rises and then measure the height above the table of that point as well as the length along the track from the loop-the-loop base. Record your data in the data table in the row for trial 2.

Repeat moving the ring stand supporting the end ramp back three more times. Record the height above the table and the length along the track of the maximum point to which the car rises in the data table.

Questions

1) Initially the angles of the start ramp and end ramp were approximately the same. As you moved the ring stand back, how did the angle of the end ramp change compared to the angle of the start ramp? Explain.

2) Based on your data in the data table, did the maximum height reached by the car change significantly as you moved the ring stand back? Explain.

3) Ideally, the car should reach the same height from which it was released. What effects might keep the car from reaching that height?

4) If you were to continue lowering the angle, how would you expect the distance the car traveled along the track to change?

5) How far would you expect the car to travel along the track if the end ramp were flat? Explain.

6) Galileo used this reasoning to arrive at the law of inertia. Complete the following,

If we can ignore __________ an object in motion will ____________________.