Lesson: Chapter 18 — Work, Energy and Power

18.1. Work 1 of 6 Reset answers

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Question 1

A man pushes as hard as he can against a wall. The wall does not move. How much work has he done on the wall?

A The work done equals his force multiplied by the time he pushed B The work done is zero, because nothing moved C The work done equals the force he applied D The work done is large, because he pushed hard

The right answer is the one marked above.

The work done is zero. Work needs a force and a change — either a change of position or a change of shape. The wall gave neither.

He will certainly feel tired, but that is work being done by his muscles inside his own body, not work done on the wall.

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