Gujarat BoardEnglish MediumSTD 9ScienceWork, Power And Energy1 Mark
Question
Work done by gravity on a man moving on horizontal surface is negative. [True/ False]
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Answer
False. Explanation: The force exerted by gravity is downward so the block should move downward. but, here the block is moving horizontally so work is not done by gravity. Mathematically, $W = F \times D \times $ cos Where is the angle between force and displacement. Here is 90 degree as direction of force and displacements of block are perpendicular to each other. So, $W = F \times D \times Cos\ 90 = 0J$
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