Fewpal
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The kinetic energy of an object of mass, m moving with a velocity of 5 m s −1 is 25 J. What will be its kinetic energy when its velocity is doubled? What will be its kinetic energy when its velocity is increased three times?

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1 Answer

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Expression for kinetic energy 

Ek= ½ mv2 

m = Mass of object 

v = Velocity of the object in ms−1 

Given that kinetic energy, Ek=25J 

(i) If the velocity of an object is doubled, then v = 5 × 2 = 10 ms−1 . Therefore, its kinetic energy becomes 4 times its original value, because it is proportional to the square of the velocity. 

Hence, kinetic energy = 25 × 4 = 100 J. 

(ii) If velocity is increased three times, then its kinetic energy becomes 9 times its original value, because it is proportional to the square of the velocity. Hence, kinetic energy = 25 × 9 = 225 J.80

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