The small slider of mass m is released from rest while in position A and then slides along the vertical-plane track. The track is smooth from A to D and rough (coeffi cient of kinetic friction k) from point D on. Determine (a) the normal force NB exerted by the track on the slider just after it passes point B, (b) the normal force NC exerted by the track on the slider as it passes the bottom point C, and (c) the distance s traveled along the incline past point D before the slider stops.