Link to Properties of a Pendulum lesson plan.
Link to Properties of a Pendulum training video.
A pendulum is a useful, simple device for physics experiments. It is easily constructed with nothing more than a piece of string of any length, and any small weight to tie on the end so that there is some tension in the string and gravity can make it oscillate back and forth.
A pendulum was the first type of mechanical clock, dating back to the time of Galileo and Newton. It exhibits periodic motion (and approximately simple harmonic motion), and experiments can be done to determine what parameters or factors go into the time it takes for one full swing, which is the period of the pendulum. Those parameters that can be tested by students include:
- the length of the string
- the mass hanging on the string
- the initial angle you start the pendulum's motion
- if you have access to a computer and the Internet, a computer simulation can be used to vary the
strength of gravity, which also affects the period of a pendulum.
This is a nice experiment that can also be used to demonstrate the approach a scientist takes when taking on an unknown phenomenon. If students know nothing about what each parameter has on the timing of a pendulum, and most will not know anything about it, they can collect data, make a graph to see the relationships, and then develop their own math formula (an empirical formula) for the pendulum. These students math models can then be compared to what the accepted formula is - but to a student, they are the scientist and they are making a discovery for themselves, rather than just reading about a pendulum. There is a video for those who want to see the mathematical analysis for the tension in a pendulum's string as it swings. There is a video for those who want to see the mathematical analysis for the oscillation of a pendulum through a small angle (simple harmonic motion).
Give it a try! Have fun with determining the properties of a pendulum.
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