How far will a you travel if you run for 10 minutes at 2 m/sec?
2 answers:
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Answer:
d. Potential energy is converted to kinetic energy; the kinetic energy is then converted into the work of bringing the body to a stop.
Explanation:
- At the beginning of the falls, when the person is still at a certain height h, the person has gravitational potential energy:
U = mgh
where m is the mass of the person, g the acceleration due to gravity, h the height above the ground.
- As the person falls down, h decreases, so the potential energy decreases; according to the law of conservation of energy, potential energy is converted into kinetic energy, since the speed of the person increases:
where v is the speed.
- Just before hitting the ground, all the potential energy has been converted into kinetic energy
- When the person hits the ground, he/she comes to a stop: so work is done by the ground on the person, because the ground applied a force required to stop the person, and the kinetic energy "lost" by the person is equal to the work done by the ground to bring the body to a stop.