A uniform plank PQ PQ\,PQ of length 6 m is supported by a pivot at its centre. A block of mass 12 kg is placed at end PPP. A second block of mass 15 kg is placed at a distance d d\,d m from the centre such that the plank rests horizontally in equilibrium.
Find the value of ddd.
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.