A laboratory balance uses a uniform beam XY XY\,XY of length 0.60 m, pivoted at its centre. A circular silicon wafer has diameter 120 mm and mass 80 g. Its edge is aligned with end XXX. A calibration mass of M M\,M g is suspended from end YYY. The beam is horizontal and in equilibrium.
Determine MMM.
State an assumption made about the wafer in this calculation.