Project : Gravity and the Pendulum

Date : October 1, 1997 to December 31,1997

Purpose : To measure the period of a pendulum at various elevations and determine if the force of gravity is constant. The force of gravity will be calculated utilizing the equation :

T = 2*PI*square root ( L / G)

where : T = period of the pendulum

L = length of the pendulum

G = force of gravity

Subjects : Physical Science, Physics

Grade level : high school

Procedure :

Step 1 : Tie a 1.2 meter length of fishing line to the ring of a ring stand or other support rod.

Step 2 : Attach the 100 gram mass to the other end of the fishing line and adjust the length to 1 meter measuring to the bottom of the mass. See diagram A

Step 3 : Using a protractor, pull the pendulum Go to an angle of approximately 10 degrees. See diagram B

Step 4 : Start stop watch as the pendulum is released and time ten complete periods. A period is defined as one complete swing with the mass returning to its original position. Insure that the pendulum swings freely and is not rubbing against any other surface. Record the results in the data table.

Step 5 : Calculate the time for a single swing by dividing the results obtained in step 4 by 10. Record the results in the data table.

Step 6 : Repeat steps 3 through 5 a minimum of four more times.

Step 7 : Utilizing a topographic map or other reliable source, record the elevation at which the experiment is being performed.

Calculations :

Step 1 : Using the information in the table, calculate the average period of the pendulum.

Step 2 : Using the values of length and average period from the experiment, calculate the force of gravity.

Step 3 : Utilizing data and calculations from cooperative experiments performed at different elevations, plot a graph of gravity (y-axis) vs. elevation (x-axis).

Step 4 : Plot a second graph comparing period of the pendulum (y-axis) vs. elevation (x-axis).

average period of the pendulum (T) =___________________

the force of gravity (G ) =___________________

Your responsibility : to e-mail the average period of the pendulum, your calculation of the force of gravity, elevation, and location to kcharles@ROE48.k12.il.us

What you will receive : a table of all the data including elevations, periods, the forces of gravity, and locations.

Go to the CD-ROM Table of Contents

© 1998 Elmwood Jr./Sr. High School