physic 問題(+20)急!!!

2010-03-24 4:44 am

A.J. Hackett se a world record of bungee jumping on the Macau Tower by jumping off the building at a height of 223 m above the ground. Hewas only 50 m above the ground when he reached the lowest position. Assume that his was 60 kg.

a)

Estimate his loss in gravitational potential energy during the fall.

b)

If 30% of the mechanical energy was lost when the cord eas stretched, ehat was the elastic potentia energy stored in the coed when Hackett reached the kowest position?

更新1:

b) If 30% of the mechanical energy was lost when the cord "was" stretched

回答 (1)

天同

2010-03-24 5:33 am

✔ 最佳答案

(a) Loss of potential energy
= 60g x (223-50) J = 103 800 J (take g, the acceleration due to gravity to be 10 m/s2)

(b) Amount of mechanical energy lost
= 0.3 x 103800 J = 31140 J
Hence, energy stored in the cord
= (103800 - 31140) J = 72 660 J

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