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Question
Answer carefully, with reason:
If the potential energy of two billiard balls depends only on the separation distance between their centres, is the collision elastic or inelastic? (Note, we are talking here of potential energy corresponding to the force during collision, not gravitational potential energy.)
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Solution
The potential energy depends on the separation distance between centres; this means that during the collision, the force acting between the bodies is conservative; therefore, energy will be conserved. Thus, the collision will be elastic.
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