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Impact and collisions — elastic impact and relative velocity For a perfectly elastic impact, relate the relative velocity after impact to the relative velocity before impact. Choose the correct statement.

Difficulty: Easy

equal to
equal and opposite to
less than
greater than

Correct Answer: equal and opposite to

Explanation:

Concept
Coefficient of restitution, e = 1 for a perfectly elastic impact.

Key relation
Relative velocity of separation = e × Relative velocity of approachFor e = 1, magnitude after impact equals magnitude before impact, but the direction reverses.

Final Answer
equal and opposite to

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