A body of mass 5 kg moves at 4 m s-1. Its kinetic energy is
- A. 10 J
- B. 20 J
- C. 40 J
- D. 80 J
Explanation
Kinetic energy is half times 5 times 4 squared, which is half times 5 times 16, giving 40 J. The common slip is to forget to square the velocity, which gives 10 J, or to forget the factor of one half, which gives 80 J.
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