Main Project Information Introduction Initial Observations & Hypothesis Materials & Equipment

Experiments Discussion Application Conclusion

Experiments

How to make pendulum?

I used Canadian pennies as a load and dental floss to make the simple pendulum. The mass of the penny is well known, 2.35 g; I found it from the Internet. By varying the number of pennies one can observe if the period of the pendulum changes with the mass of the load. I used scotch tape to tie the pennies together.

I used a hook (one is used to hang on the pictures) screwed in the door frame. If you want to try I strongly recommend to ask your parent’s permission first!

How to measure the period of oscillations?

I have noticed that it is not easy to find the period by measuring the time interval for one cycle, because the pendulum oscillates fast enough. It is much easier to measure the time intervals (t, sec) for 10 or more (depending how fast the pendulum osculates) cycles (n) and then evaluate the period as

How to measure the angle of revolution?

I used the protractor to measure the angle of revolution (Fig 2). This is an angle between the vertical and the pendulum.

Fig 2. Angle measurement

How to compare the results?

To compare the results of the experiments I defined the reference conditions:

· Angle of revolution,

· Mass, m = 11.75 g (5 Canadian pennies)

· Length, l = 0.7 m

To observe the dependence of period on the mentioned above parameters (mass, angle of revolution, length) I kept two of them constant (at reference values), and varied the third one.

Experiment 1: Period vs. Mass

I varied the mass by varying the number of pennies from 5 (11.75g) to 12 (28.2g). In each measurement of Experiment 1 I kept the angle of revolution,, and Length, l = 0.7 m.

Plot 1. Period vs. Mass

Experiment 2: Period vs. Length

I varied the length by varying the length of the rope from 0.2 m to 1.2 m. In each measurement of Experiment 2 I kept the mass, m = 11.75 g (5 Canadian pennies), and the angle of revolution, .

Plot 2. Period vs. Length

Experiment 3: Period vs. Angle of Revolution

I varied the angle of from to (Fig. 2). In each measurement of Experiment 3 I kept the kept the mass, m = 11.75 g (5 Canadian pennies), and the Length, l = 0.7 m.

Plot 3. Period vs. Angle

Main Project Information Introduction Initial Observations & Hypothesis Materials & Equipment

Experiments Discussion Application Conclusion