Take Home Lab #2

Take Home Lab #2

Question:  Which variables affect the period of a pendulum?

Safety:  Do not swing the pendulum in a dangerous manner. Washers can be a choking hazard, so keep them out of the reach of children.

Materials: Thread or dental floss, washers, a timer

Procedure: In this lab, you will determine which of three factors determines the period of a pendulum. A pendulum is a weight handing from a string. You will use a piece of thread or dental floss (approximately 50 cm) and washers to make your pendulum. The period is how long it takes the pendulum to swing back and forth once. The three factors, or variables, that you will test are the mass at the end of the pendulum, the angle from which the pendulum is dropped, and the length of the pendulum. You need to follow the rules of a good experiment (i.e., changing only one variable at a time, repeating each trial more than once, etc.). This procedure will mainly be determined by you but here are some tips:

1. Do not swing the pendulum from high angles (greater than 35°), or it will not swing smoothly.

2. It will be nearly impossible to measure one swing of the pendulum accurately; you will want to let the pendulum swing multiple times and then divide the total number of swings.

3. You do not have to measure the exact masses, angles and lengths of the pendulum. You can use low, medium, and high angles; short, medium, and long lengths; and one, two, and three washers (or small, medium, and large).

4. If one or more of the factors does affect the period of the pendulum, it will affect it greatly. Do not let periods of 1.21 and 1.23 sec make you think there was a change. The difference will be more like periods of 1.21 and 3.23 sec.

1. Data charts: Because you will determine the procedure, you will also determine the data charts. Keep in mind that you should test each variable (length, angle and mass) at three different levels (low, medium, and high). You also must conduct there trials for each different variable. That means you have at least 27 trials.

Post-Lab Questions:

2. Which variable or variables had the biggest effect on the period of the pendulum?

3. Can you relate this information to your experiences on or around playground springs? Explain.

4. Draw three line graphs or bar graphs. Each graph should have the variable being tested on the x-axis and the period (time in seconds) on the y-axis. Start the y-axis at o to avoid amplifying small changes.