# Evan's Space

## Wonders of Physics # Factors that affect the period T of a pendulum

Period, T, is the time taken for one complete oscillation.

The period T of a pendulum is affected by the following factors.
1) the length of the pendulum:
– the longer the length, the longer the period (i.e. swing slower)

2) the gravitational field strength, g
– the greater the g, the shorter the period (i.e. swing faster)
(e.g. the g on earth is 10 N/kg while that on the moon is 1.6 N/kg, hence the period on           the moon will be longer)

NOTE: (common misconceptions)
Period, T, of the pendulum is NOT affected by
1) the angle of release (as long as the angle of release is between 10 to 15 degrees)
(if the angle of release is small, the swing will not be fast and air resistance will not be         significant)
2) the mass of the pendulum ball

Refer to the video below for the demonstration of the above concepts.

Pendulum: Displacement-time vs KE-time graphs

Click here to understand the concepts of Displacement-time vs Kinetic Energy-time graphs of a pendulum

How to set up the pendulum experiment?

### 5 thoughts on “Factors that affect the period T of a pendulum”

1. What’s the most suitable angle to displace a pendulum through?

• Usually any angle between 10 to 15 degree is alright. As long as the angle is small, and the speed of the pendulum is not too fast, air resistance is negligible.

2. Does air resistance slow down the time period of the swing?

• Yes air resistance will increase the period. That is why you are supposed to release the pendulum bob at small angles like 10 to 15 degrees. So that the speed is not too fast hence air resistance is kept to a minimum.