For demonstrating the concept Parallelogram and polygon law of forces and Lami’s theorem about static equilibrium which relates to the magnitudes of three forces-coplanar, concurrent and non-collinear which keep the object in static equilibrium. This apparatus comprises board of size about 65 x 50cm, with two aluminium pulleys, 50mm diameter, on clamp for mounting on board in any desired position. Comes with three mass hangers and 12 slotted masses, each of 50g each.