A boy with 81.6 kg weight walks up a plank BD (distance from B to D is 3m), which rests on a ramp sloping at 300 to the horizontal. It rests on a frictionless roller support at D.

(i) Draw possible free body diagrams capturing the boy's weight when he is at B with external force, reaction forces at B and D, and friction at B.

(ii) What is the value of the coefficient of static friction, if the plank does not slide down the slope, when he is at Point B? (iii) Can the boy reach Point D? Why? (5marks)

3m B 450 300