simple question: a movable block on a movable wedge on some frictionless ground. we know all masses, angles, and there is no friction. the block starts on the wedge at some height h, and slides down the wedge. the block moves forwards, and the wedge moves backwards. what is the velocity of the wedge, the moment before the block hits the ground - i.e. block still on wedge? i tried this question. however, i could only get the velocity of the wedge, after the block is totally off the wedge by conservation of energy and momentum.