Two small identical disks,each of mass m lie on a smooth horizontal plane. The disks are interconnected by a light non deformed spring of length L and stiffness X. At a certain moment one disk is given velocity v. Find maximum elongation of the spring.

The problem is solved easily when solven in centre of mass frame. My doubt is how can we solve it from a frame of reference not attached to com?.


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The spring will first expand and then contract.

At the moment of the transition between expanding and contracting, the spring will be at its maximum elongation. At the same moment, the velocity of both disks will be the same.

Taking that into account and applying the energy and the momentum conservation laws you should be able to find the answer.


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