If a 14 kg mass, moving at 10 m/s to the right, hits and sticks to a 9 kg mass, moving at 7 m/s to the left, and they travel off together at the same speed, find that speed. Hint: here, the masses are moving in opposite directions, so the velocities should have opposite signs. Call "to the right" positive and "to the left" negative. Use the "hit and stick" or inelastic formula