The mass of a regulation tennis ball is 530 g although it ca

The mass of a regulation tennis ball is 53.0 g (although it can vary slightly), and tests have shown that the ball is in contact with the tennis racket for 33.0 ms . (This number can also vary, depending on the racket and swing.) We assume a 33.0 ms contact time in this problem. In the 2011 Davis Cup competition, Ivo Karlovic made one of the fastest recorded serves in history, which was clocked at 156 mi/h (70 m/s)

What impulse and what average force did Karlovic exert on the tennis ball in his record serve?

What average force did Karlovic exert on the tennis ball in his record serve?

If his opponent returned this serve with a speed of 60.0 m/s , what impulse did his opponent exert on the ball, assuming purely horizontal motion?

If his opponent returned this serve with a speed of 60.0 m/s , what average force did his opponent exert on the ball, assuming purely horizontal motion?

Solution

P = m * (v₂ - v₁)

= 0.053 * (70 - 0)

= 3.71 kg.m/s

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F = P / delta t

= 3.71 / 0.033 s

= 112 N

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F = [ 0.053 * (70 + 60 )] / (0.033 s)

= 208.8 N

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impulse = 208.8 * 0.033

= 6.89 kg.m/s