A 5.10 kg watermelon is dropped from rest from the roof of a 30.0 m tall building
and feels no appreciable air resistance.
1. Calculate the work done by gravity on the watermelon during its displacement from the roof to the ground.
W = ? J
2. Just before it strikes the ground, what is the watermelon's kinetic energy?
K = ? J
3. Just before it strikes the ground, what is the watermelon's speed?
v= ? m/s
work energy
2012-10-19 6:39 am
回答 (1)
2012-10-19 4:26 pm
✔ 最佳答案
1. W = 5.1g x 30 J = 1530 Jwhere g is the acceleration due to gravity, taken to be 10 m/s2
2. By conservation of energy, kinetic energy = 1530 J
3. Speed = square-root[2 x 1530/5.1] m/s = 24.5 m/s
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