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NEET UG PHYSICS MCQ: WORK-ENERGY-POWER

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A machine which is 75% efficient uses 12 J of energy in lifting up a 1 kg mass through a certain distance. The mass is then allowed to fall through, that distance. The velocity of the ball at the end of its fall is

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Correct option: C

\sqrt {18} \mathrm{\;m}{\mathrm{s}^{ - 1}}

Option C (

\sqrt {18} \mathrm{\;m}{\mathrm{s}^{ - 1}}

) is correct because 75% of the 12 J energy is converted to potential energy (mgh), which then converts to kinetic energy (1/2 mv²) during the fall. Solving for v gives

\sqrt{18}

m/s.

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