Block ?A? in Fig weighs 2.40 N and block ?B? weighs 3.60 N. The coefficient of kinetic friction between all surfaces is 0.300. Find the magnitude of the horizontal force necessary to drag block ?B? to the left at constant speed (a) if ?A? rests on B? and moves with it (Fig. 1). (b) If ?A? is held at rest (Fig. 2). Figure 1: Figure 2:

Solution 73P Step 1 of 3: The block is moving with constant speed so the acceleration is zero(a=0) a)Total weight of the two blocks,w = w + A = 6 B F =ya y n=w=6 N f = n = 1.8 N k k F =xa x n=w=6 N F = f k 1.8 N