Lesson: Chapter 18 — Work, Energy and Power

18.1. Work 6 of 6 Reset answers

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Question 6

An object of mass 5 kg is raised through a height of 3 m. How much work is done? (g = 10 m s^-2)

A 15 J B 50 J C 1.5 J D 150 J

The right answer is the one marked above.

150 J. weight = 5 kg × 10 m s^-2 = 50 N, and work = 50 N × 3 m = 150 J.

15 J is what you get by putting the mass of 5 kg straight into the formula. A mass in kilograms is not a force, and it has to be turned into a weight in newtons first.

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