A) a block of mass, m, is pushed up against a spring, compressing it a distance x, and is then released. the spring projects the block along a frictionless horizontal surface, giving the block a speed v. the same spring projects a second block of mass 4m, giving it a speed 3v. what distance was the spring compressed in the second case?
b) initially a body moves in one direction and has kinetic energy k. then it moves in the opposite direction with three times its initial speed. what is the kinetic energy now?

Two manned satellites approaching one another at a relative speed of 0.550 m/s intend to dock. the first has a mass of 2.50 ✕ 103 kg, and the second a mass of 7.50 ✕ 103 kg. assume that the positive direction is directed from the second satellite towards the first satellite. (a) calculate the final velocity after docking, in the frame of reference in which the first satellite was originally at rest.(b) what is the loss of kinetic energy in this inelastic collision? (c) repeat both parts, in the frame of reference in which the second satellite was originally at rest. final velocity(d) loss of kinetic energy = ?