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A ball is dropped from height h and strikes an inclined plane of inclination theta. If, immediately after the impact, the ball moves horizontally, what is the coefficient of restitution?

1. tan²(theta)
2. cot(theta)
3. tan(theta)
4. cot²(theta)

Correct answer: tan²(theta)

Solution

Resolving the downward velocity into normal and tangential components and applying e to the normal component, the requirement that the rebound velocity be horizontal yields e = tan²(theta).

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