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Work And Energy — Science STD 9 — Question

Gujarat BoardEnglish MediumSTD 9ScienceWork And Energy2 Marks
Question
When is the work done said to be negative?
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Answer

When displacement of the body is in direction opposite to direction of force.
Example: when a person lifts a weight then the displacement of the body is in direction opposite to Gravitational Force and thus it can be said that the work done on the body by gravity is NEGATIVE (angle between Gravitational Force and Displacement is 180 degree and cos 180 = -1).

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