At the scintillating game against the New England Patriots yesterday,Jeremy Kerley (188 lbs mass) ca

题目

At the scintillating game against the New England Patriots yesterday,Jeremy Kerley (188 lbs mass) caught a touchdown pass.To catch the ball thrown by Geno Smith he leaped above the defender at the front left corner of the end zone.In the process he first lowered his body to prepare to launch himself.Let’s assume that when he squatted down before he jumped,his center of mass (just below his belly button) was about 14 inches lower than his normal standing position.Assuming that his hang time was 0.8 s,what was the force he exerted on the ground when he jumped?(Hint:First calculate the initial velocity when he jumped up.Then,consider how that velocity was generated from the squat position.Was there an acceleration involved?)

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