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.
53 exam-style questions on OCR A Level Maths 3.4 Moments (A-level only), covering 3.4.1 Moment of a force (A-level only), 3.4.2 Equilibrium of a rigid body (A-level only), and 3.4.3 Moments in static contexts (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.