A laboratory balance uses a uniform beam XY XY\,XY of length 0.6 m which is pivoted at its center. To calibrate the scale, a circular silicon wafer with a diameter of 120 mm and a mass of 80 g is placed on the beam.
The wafer is positioned such that its edge is perfectly aligned with end XXX. A calibration weight of mass M gramsM \text{ grams}M grams is suspended from the other end of the beam at Y Y\,Y using a light inextensible string.
Given that the beam is in equilibrium in a horizontal position, determine the value of MMM.
State an assumption made about the silicon wafer to perform this calculation.