Pendulum

Learning Objectives

Determine experimentally the effect of the following on the period:

	pendulum bob mass,
	pendulum length, and
	starting angle.

Use graphical methods to determine the relationship between the variables.

Equipment

Stopwatch, meter stick, half-meter stick, protractor, pendulum clamp, string and masses.

3 pendulums setup 1 pendulum setup

Click to Enlarge

Procedure (groups of 4)

Mass Relationship to the the Period

1. Use three pendulums to determine the relationship of mass to the period. Click here to view the period of three pendulums

	Pull the three pendulums back and start their swing all together. For safety, do not exceed 30 degrees!
	Three students should function as time keepers. Each student should time one mass.
	Allow the mass to complete one period, then each student should measure the time for their mass to complete the next five (5) periods.
	Record the time for each mass on the Pendulum Data Collection Tool.

Starting Angle Relationship to the Period

2. Use the single pendulum to determine the relationship of the starting angle to the period for five (5) different angles.

Click here to view the period of one pendulum

	One student should use a protractor to measure the starting angle.
	Pull the single pendulum back and start its swing. For safety, do not exceed 30 degrees!
	Two students should function as time keepers, and average their times for each angle.
	Allow the mass to complete one period, then measure the time for their mass to complete the next five (5) periods.
	Record the average time for the 5 (five) angles on the Data Tool.

Pendulum Length to the Period

3. Use the single pendulum to determine the relationship of the pendulum length to the period for five (5) different lengths. You choose the lengths at least 10 cm apart from each other.

	Measure the length of the pendulum from the center of the bob to the pendulum clamp.
	Pull the single pendulum back and start its swing. For safety, do not exceed 30 degrees!
	Two students should function as time keepers, and average their two times for each length.
	Allow the mass to complete one period, then measure the time for their mass to complete the next five (5) periods.
	Record the average time for the 5 (five) lengths on the Data Tool.

4. Calculate the expected period from Galileo's equation:

Period = L must be converted to m