P. 4507. Two small balls are threaded to a horizontal frictionless rod which is attached to the wall. The heavy ball of mass M is moving towards the wall, and the other light ball of mass m (mM) is at rest at a distance of L measured from the wall. After the totally elastic collision, the light ball of mass m moves towards the wall and collides with it elastically. Then it moves towards the heavy ball and collides with it and the process is repeated. To what distance can the heavy ball approach the wall? (The two balls can be considered as pointlike objects.)
Deadline expired on 11 February 2013.