A uniform plank of length5.0m rests horizontally on two bricks that are 0.5m from either end..a child of 200n stands on one end of the plank and causes the other end to lift,so it is no longer supported at the end.calculate the weight of the plank
the situation is symmetrical so you might as well assume the child stands on the right hand end of the plank and take moments about the right hand brick. The mass of the plank acts at the centre of mass of the plank which will be at the plank's mid point (because the question tells us it is uniform)