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InterviewSolution
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The kinetic energy of an object of mass` m moving with a velocity of 5 m//s is 25 J. What will be its kinetic energy when its velocity is doubled ? What will be its kinetic energy - when its velocity si increased three times ? |
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Answer» Here, kinetic energy of the object, `E_k = 25J` velocity of the object, `upsilon = 5 m//s` `As E_k= (1)/(2)m upsilon^2, m = (2E_k)/(upsilon^2) = (2xx25J)/((5//s)^2) = 2kg` Kinetic energy of the object when its velocity is doubled `(i.e., upsilon = 10 m//s)` `(1)/(2)m upsilon^2 = (1)/(2) (2kg) (10m//s)^2 = 100 J` Kinetic energy of the object when its velocity in increased three times `(i.e., upsilon =15 m//s)` `=(1)/(2)m upsilon^2 = (1)/(2) (2kg) (15m//s)^2 = 225 J` Aliter. Since `E_k prop upsilon^2` (as m is constant), (i) when `upsilon` is doubled, `E_k` becomes `(2)^2 = 4` times its previous value, i.e.,` 4xx25 J = 100 J` (ii) when `upsilon` is increased three times, `E_k` becomes `(3)^9 = 9` times it previous value, i.e., `9 xx 25 J = 225 J` |
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