It is used to verify the law of parallelogram of forces, which states that if two forces acting at a point can be represented by two adjacent sides of a parallelogram, then the resultant of these two forces can be represented in magnitude and direction by the diagonal of the parallelogram which is passing through the same point.
The apparatus consists of a board with dimensions= 65x50cm, with two aluminium pulleys (50mm diameter) on a clamp, for mounting in any position.
It comes with three nickel-plated iron hangers (50 gm each) and a cord.
12 slotted weights of 50 gm each are also provided with the apparatus.