Comprises of aluminum disc of dia 15cm approximately with a concentric groove in which balancing weights are placed which help in setting the disc horizontally. An inverted U-shaped metal frame is fitted on the aluminum disc with a chuck at its mid-point. A steel wire is used to suspend the frame from a vertical stand which has a circular base fitted and leveling screws. A mirror is attached at the centre of the frame to count the number of oscillations. Supplied with masses of regular geometric shapes(Rectangular, Square, circular and triangular).