A small puck of mass m asn velcity v slider along a horizonal plane. The puck meets a "hill " of mass 3 m and height h that can also move along the plane . The puck begins to slide up the " hill" [see fig 4E.4 (a)] . If the hill is initially at rest m what value of v provides for the maxium subsequent velocity us of the " hill " ? Assume that all surface are frictionless.