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.
33 exam-style questions on CCEA A Level Maths 4.2.1 Moments (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.