A pendulum is a point mass - sometimes called a 'bob' - connected to a string, rod or rope, that experiences simple harmonic motion as it swings back and forth.

The equation that describes its period T is:

where l is the length of the string and g is the acceleration due to gravity.

The mathematical treatment that results in the above equation assumes the mass is a 'point' so that it is not experiencing air resistance, it also assumes that it swings without friction at the pivot point and that the string is inextensible.

The equilibrium position of the pendulum is the position when the mass is hanging directly downward.

Here is an interactive activity to 'enrich' your study of this topic.

Click here to find out about the history of the pendulum and its development into a timing mechanism.

Click here to consider the forces acting

Click here to consider the energy transitions