In the diagram on the right, a plank weighing 120 N is supported by two trestles at points A and B. A man weighing 480 N is standing on 1m mass centre of of plane the plank.. a Redraw the diagram, showing all the forces acting on the plank. b Calculate the total clockwise moment of the two weights about A. c Use the principle of moments to calculate the upward force from weight of man 480 N weight of plank 120 N the trestle at B. d What is the total downward force on the tresties? tist e What is the upward force from the trestle at A? f The man now walks past A towards the left-hand end of the plank. What is the upward force from the trestle at 8 at the instant the plank starts to tip? g How far is the man from A as the plank tips