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A mass of `50 kg` is raised through a certain height by a machine whose efficiency is `90%` , the energy spend is `5000 J`. If the mass is now released, its `KE` on hitting the ground shall be:A. `5000 J`B. `4500 J`C. `4000 J`D. `5500 J` |
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Answer» Because the efficiency of machine is `90%`, hence potential energy gained by mass `= (90)/(100) xx energy = (90)/(100) xx 5000 J = 4500 J` When the mass is released now, gain in `KE` on hitting the ground = loss of potential energy =` 4500 J` |
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