Rod on a Plane: Calculating Angular and Linear Motion After Impact"

[Delta2]

Yes i agree, quite hard problem, testing to the extreme the understanding of concepts and principles.
Is it college level or university level exams this is from?

 

[haruspex]

If we don't make this assumption, then a mini paradox will appear if we do the balance of the kinetic energy when the particle returns to A. Somehow the total kinetic energy will be increased (in point A , with regards to point B after the inelastic collision), and we won't be able to infer where this surplus "ghost" energy has come from.

Ah yes, it wouldn’t make it back to A if it were not elastic.

 

[Delta2]

Ah yes, it wouldn’t make it back to A if it were not elastic.

Thanks for resolving the paradox, if i tell you that i spend part of last night before sleep thinking where does the surplus of kinetic energy comes from you ll laugh with me won't you?

 

[Nexus99]

Yes i agree, quite hard problem, testing to the extreme the understanding of concepts and principles.
Is it college level or university level exams this is from?

University.