Introduction

This experiment aims to find the relationship between surface area of a pendulum bob and the time taken for the pendulum to come to rest.

Equipment

Clamp & stand

Fine wire or fishing line

Pendulum bobs of differing cross sectional area (spherical or cylindrical bobs will work best)

Stopclock

Ruler

Method

The pendulum should be set up with a known length of wire, e.g. 50cm between pivot and the centre of mass of the bob.

The bob should be raised to one side such that it is elevated 10cm from its rest position and the line is taut.

As the bob is released the stopclock should be started and the pendulum should be observed until it comes to rest, at which point the stopclock should be stopped and time recorded.

The experiment should be repeated three times with each bob.

Care should be taken to ensure that the centre of mass is at the same distance from the pivot so that the effective length of the pendulum remains constant.

Analysis

The cross sectional surface area of the bob should be plotted against the time taken for the bob to come to rest.