- Two identical trolleys of mass M, each carrying a person of mass m, are situated on parallel rails. One of the trolleys is initially standing, and the other moving with velocity v1. At the moment when the moving trolley is passing the standing one, the two persons simultaneously jump perpendicular to the rails, so that the first one lands at the second trolley at the same time as the second one lands at the first trolley. Find the resulting velocities of the trolleys upon this exchange.

O t = t1 t = t2