WB7 A uniform plank has mass 40 kg and length 4 m. AB It is supported in a horizontal position by two smooth pivots, one at the end the other at A, the point of the plank where = 3 m, as shown in the diagram above. C AC A man of mass 80 kg stands on the plank which remains in equilibrium. The magnitudes of the reactions at the two pivots are each equal to newtons. R By modelling the plank as a rod and the man as a particle, find a) the value of R, b) the distance of the man from A.
WB7 A uniform plank AB has mass 40 kg and length 4 m. It is supported in a horizontal position by two smooth pivots, one at the end A, the other at the point C of the plank where AC = 3 m, as shown in the diagram above. A man of mass 80 kg stands on the plank which remains in equilibrium. The magnitudes of the reactions at the two pivots are each equal to R newtons. By modelling the plank as a rod and the man as a particle, find a) the value of R, b) the distance of the man from A.