In this question use g=9.8g = 9.8g=9.8 m s−2^{-2}−2.
A uniform plank AB AB\,AB of length 4 m and mass 25 kg rests on a horizontal platform, with the end B B\,B projecting over the edge of the platform. The edge of the platform is at the point C C\,C of the plank, where AC=2.5AC = 2.5AC=2.5 m.
A woman of mass 60 kg steps onto the plank at A A\,A and walks slowly towards BBB.
Find the distance from A A\,A at which the plank begins to tilt.
56 exam-style questions on OCR (MEI) A Level Maths 3.6 Rigid Bodies (A-level only), covering 3.6.1 Moment of a force (A-level only), 3.6.2 Equilibrium of a rigid body (A-level only), 3.6.3 Turning effect of forces (A-level only), and 3.6.4 Weight acting through a point (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.