Seems like a problem dealing with the conservation of angular momentum, although it would help if a diagram of how the moving mass and (stationary?) cylinder are arranged.
A Cylinder (mass = 10kg , radius= 0.2m) is mounted between two walls (Cylinder can rotate freely). At the top of the first wall a mass of 5 kg moving with a constant velocity 10m/s and touch the cylinder and jump to the other wall.Find out the velocity when it leave from the cylinder?
Please show me the way to solve this problem.