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?
Mass of the object = m
Velocity of the object = v = 5 m/s
Kinetic energy, EK = 25 J
(i) If the velocity of an object is doubled, then v = 5 × 2 = 10 m/s
Therefore, its kinetic energy becomes 4 times 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 because it is proportional to the square of the velocity. Hence, kinetic energy = 25 × 9 = 225 J.
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