Galileo Pendulum Experiment

Student Data Sheet

 

I. Varying Amplitude (how far it swings) :

A. Let a pendulum swing for a while and watch it as it wears down.  Does it nearly return to the point where it was let go after the first swing? What principle of Galileo’s does this illustrate? Why would Aristotle have disagreed?

As it starts to swing less and less does the period (the time for it return to its starting point) of its oscillation decrease?

 

B. Varying the Amplitude and Measuring Period:

1. Medium Amplitude. Have a timer measure a 15 second period. Drop the pendulum from medium height when the timer says start and count the number of  complete swings it makes before they say stop.

2. Low Amplitude: Make the same measurement, this time dropping the pendulum from less height.

3. High Amplitude: Make the same measurement, this time dropping the pendulum from more height. Don’t start it so high it doesn’t swing freely.

 

Amplitude

Medium

Low

High

# swings/15 seconds

 

 

 

# swings/15 seconds

 

 

 

Does the period vary with amplitude? Can you figure out why? Why do you think this is important?

 

II. Varying the length of the string:

Make long pendulum, and measure how many swings it makes in 15 seconds. Decrease the length of the string by ½ and measure again. Decrease by another ½ and measure again. You should be able to decrease it by ½ one more time.

 

Length

Initial length

1/2

1/4

1/8

# swings/15 seconds

 

 

 

 

# swings/15 seconds

 

 

 

 

 

Does the number of swings change the by the same amount each time you cut the string length in half. Can you figure out the mathematical relationship between the two? Is it surprising that there should be a regular relationship between the two that doesn’t vary?

 

III. Different Weights:

  1. Control. First release two identical pendulums at the same time. How many swings do they stay in sync? How far out of sync do they get after 15 seconds?  Why do you think they get out of sync a little? Why is it important to do two identical ones first?
  2. Different weights. Release the heavy nut with the lighter ring clamp. How many swings do they stay in sync? How far out of sync do they get after 15 seconds? What does this show? Why was this result important to Galileo?
  3. If you want, try some of the lighter pendulums. What do you think causes the difference in results?