A Center Raft -L- person is standing at one end of a uniform raft of length L that is floating motionless on water, as shown above. The center of mass of the person-raft system is a distance d from the center of the raft. The person then walks to the other end of the raft. If friction between the raft and the water is negligible, how far does the raft ove relative to the water? C + L/2 L d/2 0 d Center of Mass of System 2d

Three ice skaters, numbered 1, 2, and 3, stand in a line, each with her hands on the shoulders of the skater in front. Skater 3, at the rear, pushes on skater 2. Identify all the action/ reaction pairs of forces between the three skaters. Draw a free-body diagram for skater 2, in the middle. Assume the ice is frictionless.

1. Two blocks are connected by a pulley system shown in the figure below. Neglect friction between the block on the left and the ramp sloped at angle 0. Suppose that the block on the left has mass m, and that the block on the right is moving downward at a constant speed v. m Given m, 0, and v, answer the questions below. (a) Find the mass of the block on the right? (b) Find the velocity of the block on the left. (c) If the block on the right was moving at a constant speed v upward, instead of downward, how would your answer to Question la change?

2-Determine the magnitude ( P) of the B W=30 N horizontal force required to initiate motion of the block of mass (m.) for the cases : a-Pis applied to the right. b-Pis applied to the lift. u=0.5 30° P(a) mg P(b