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.
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.