2. A 18 kg rock starting from rest free falls through a distance of 7.0 m with no air resistance. Find the momentum change of the rock caused by its fall and the resulting change in the magnitude of earth's velocity. Earth's mass is 6.0 1024 kg. Show all your work, assuming the rock-earth system is closed. Answer: boy & sled Vinitial falling snow Vfinal boy & sled, with snow Score 3. A 35 kg child on a 4.2 kg sled is sliding at 5.0 m/s, with negligible friction, along an icy, horizontal surface. As the sled passes underneath a tree, a 6.2 kg mass of snow falls vertically and lands on the moving sled. Calculate the final velocity of the sled. Calculate the final velocity of the sled. Show your work. Answer: