This experiment is designed to reinforce the general principle that the work done, particularly by a variable force, can be determined simply by measuring the area under the graph of force and distance moved.
The equipment is deliberately simple so that concepts are readily grasped. It is a companion experiment to HFC6, which is concerned with the work done by available vertical force.
A pivoted arm carrying a load hanger at its end is restrained by a spring balance at right angles to the arm. The angular position of the arm is indicated by a protractor scale attached to the back board.
The effort is the force needed to hold the weighted arm at a particular angle. This can be repeated for several different weights.
The back board easily sits onto a bench.