If a body a mass of 2 kg is raised vertically through 2m, then the work done will be _________________?
Correct answer: C. 39.2 J
- A. 38.2 J
- B. 392.1 J
- C. 39.2 J
- D. 3.92 J
Explanation
The work done in raising the body equals its gain in gravitational potential energy: W = mgh = 2 kg x 9.8 m s-2 x 2 m = 39.2 J. The likely wrong choice is b, 392.1 J, which comes from an arithmetic or decimal-place error and is ten times too large.
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Potential energy is energy stored because of position or configuration, including gravitational potential energy near Earth's surface and elastic energy in a stretched or compressed spring. Questions use changes in potential energy and conservation of mechanical energy, while distinguishing a chosen reference level from an absolute zero of energy.
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