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A 10 g ball moves normal to a wall, hits it, and rebounds along the same straight line with unchanged speed. If the impulse delivered to the wall is 0.54 N·s, what is the speed of the ball?

1. 27 m s⁻¹
2. 3.7 m s⁻¹
3. 54 m s⁻¹
4. 37 m s⁻¹

Correct answer: 27 m s⁻¹

Solution

Impulse on wall = 2 m v = 0.54 N.s with m=0.010 kg, so v = 0.54/(2x0.010) = 27 m/s.

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