A stone is dropped at t = O. A second stone, with 2 times the mass of the rst, is dropped from the same point at t = 65 ms. (a) How far below the release point is the center of mass of the two stones at t = 430 ms? (Neither stone has yet reached the ground.) (b) How fast is the center of mass of the two-stone system moving at that time? (a) Number n I Units m (b) Number n I Units m/s 0 In the gure, a climber with a weight of 540 N is held by a belay rope connected to her climbing harness and belay device; the force of the rope on her has a line of action through her center of mass. The indicated angles are 9 = 35 and (p = 25'. If her feet are on the verge of sliding on the vertical wall, what is the coefcient of static friction between her climbing shoes and the wall