1. The 200-lb block shown has impending motion up the plane caused by the horizontal force of 400 lb. Determine the coefficient of static friction between the contact surfaces. Ans. As = 0.66 200 b 400 b 30 2. Determine The uniform 10kg ladder in the figure rests against the smooth wall at B, and the end A rests on the rough horizontal plane for which the coefficient of static friction is s = 0.3. Determine the angle of inclination @ of the ladder and the normal reaction at B if the ladder is on the verge of slipping. Ans. 29.4N, 59 3. The uniform stone shown has a mass of 500 kg and is held in the horizontal position using a wedge at B. If the coefficient of static friction is us = 0.3 at the surfaces of contact, determine the minimum force P needed to remove the wedge. Assume that the stone does not slip at 4. Ans. 1.15KN 4. The block and tackle shown are used to lower a 150-lb load. Each of the 3-in. diameter pulleys rotates on a 0.5-in.-diameter axle. Knowing that the coefficient of static friction is 0.20, determine the tension in cach portion of the rope as the load is slowly raised. Ans. TAn = 77.5LB, Tcn= 72.5 LB, T=67.8LB F 150