In order to weigh aboy in the laboratory.a uniform plank of wood AB 3m long and having amass of 8 kg is pivoted about a point 0.5m from A.The boy stands 0.3m from Aand a mass of 2 kg is placed0.5m from B in order to balance the plank horizontally.Calculate. the mass of the boy.Also find the reaction force exerted by the pivot on the plank.
8 answers