Welcome to practical physicsPracticle physics - practical activities designed for use in the classroom with 11 to 19 year olds

Simple pendulum experiments

In different teaching schemes, class experiments with pendulums take several forms:  

  • experiments to demonstrate relationships or verify laws 
  • training in techniques of timing and observing 
  • scientific investigation 
  • an accurate measurement of g  

Experiments to demonstrate relationships or verify laws 
Many students welcome routine experiments with definite instructions and a clear outcome. This form of experiment, in which the answer is stated first, does not demonstrate real science practice but can show that physical phenomena behave predictably. 
Training in techniques of timing and observing 
You may think that training in techniques is useful, but training does not transfer easily. It is unlikely to spread to other fields of science, unless you ensure that its potential value makes a strong impression. 
A scientific investigation 
Even if students know that you are well aware of the 'answer', that there is some 'formula' that describes how pendulums behave, they can do genuine scientific work if they regard the experiment as an investigation. 
The experiment itself may be almost the same as 'verifying the formula' but the instructions need an essential twist. Ask students to find something out, not show that what you have already said is true. Say what should be measured (e.g. many swings should be timed) or what relationships should be investigated. Certainly do not say what results are to be expected. 
An accurate measurement of g 
Advanced students may enjoy extracting the value of the gravitational field strength, g, by this indirect method.