5. The diagram shows a ladder of weight 500 N resting on two surfaces at points A and B. Dimensions are as indicated. The coefficient of friction at all contacting surfaces is 0.4. Determine the maximum height to which a person of weight 1200 N can climb the ladder before slip occurs.

The coeffient of static friction between the uniform bar AB of weight W and the ground is 0.45. Find the smallest angle and the corresponding force P that would initiate simultaneous tipping and sliding of the bar.

A uniform plank is supported by a fixed support at A and a drum at B that rotates clockwise. The coefficients of static and kinetic friction for the two points of contact are as shown. Determine whether the plank moves from the position shown if (a) the plank is placed in position before the drum is set in motion; and (b) the plank is first placed on the support at A and then lowered onto the drum, which is already rotating.

Two identical chairs, each weighing 14 lb, are stacked as shown. The center of gravity of each chair is denoted by G. The coefficient of static friction is 0.2 at B (the contact point between the chairs) and 0.35 at A, C, and D. Determine the smallest force P that would cause sliding.