Kinetic energy of a body moving with a speed of 10 m/s is 30 J. If its speed becomes 30 m/s, its kinetic energy will be
Correct answer: B. 90 J
- A. 10 J
- B. 90 J
- C. 180 J
- D. 270 J
Explanation
Kinetic energy (K.E.) is given by the formula K.E.=1/2 mv^2, where m is the mass of the body and v is its velocity. If the speed triples from 10 m/s to 30 m/s, the kinetic energy increases by a factor of 3^2=9. Therefore, the new kinetic energy is 30 J×9=270 J30J×9=270J.Incorrect Options Explanation:(a) 10 J: This is the original kinetic energy, not the new one.(c) 180 J: This value doesn't reflect the increase in kinetic energy when the speed triples.(d) 270 J: This value is the correct increase in kinetic energy but doesn't correspond to the final kinetic energy when the speed becomes 30 m/s.
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Work transfers energy when a force causes displacement, while kinetic energy, gravitational potential energy and power describe motion, position and the rate of energy transfer. The work-energy theorem links net work with change in kinetic energy, and efficiency accounts for energy losses rather than treating them as energy destruction.
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