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प्रश्न
A man carrying a suitcase in his hand is walking horizontally. What is the work done against gravity?
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उत्तर
The displacement of the man and suitcase is along the horizontal direction. Thus, the angle between the displacement and the force of gravity is 90°;
Thus, W = Fd cos 90° = 0
Hence, no work is done against gravity in this case.
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संबंधित प्रश्न
In each of the following a force, F is acting on an object of mass, m. The direction of displacement is from west to east, as shown by the longer arrow. Observe the diagrams carefully and state whether the work done by the force is negative, positive or zero.
State the S.I. unit of work and define it.
State the S.I. unit of energy.
A water pump raises 50 litres of water through a height of 25 m in 5 s. Calculate the power of the pump required.
(Take g = 10 N kg-1 and density of water = 1000 kg m-3)
Fill in the blank with suitable word :
1 joule is the work done when a force of 1 __________ moves an object through a distance of one __________ in the direction of __________.
