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प्रश्न
How much energy is gained by a box of mass 20 kg when a man, runs carrying the box with a speed of 3 m/s-1 to catch the bus?
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उत्तर
Mass of box=20 kg
Work done, Kinetic energy of man
`= 1/2 xx "mass" xx ("Velocity")^2`
`= 1/2 xx 20 xx (3)^2`
`= 1/2 xx 20 xx 9` = 90 J
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