Question

Calculate the change in the kinetic energy of a moving body if its velocity is reduced to 1/3rd of the intial velocity
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Answer 1

Answer:

Let a body of mass 'm' is moving with velocity 'v' m/s. the initial kinetic energy is given by Now, the velocity is reduced to 1/3rd or the initial velocity. The final kinetic energy is given by. So, K.E. becomes 1/9th of its initial K.E.

Answer 2

Answer:

Given: Initial velocity =v; Final velocity =3v

Initial kinetic energy k1=21×m×v2

Final kinetic energy k2=21×m×(3v)2=91×21mv2

Change in kinetic energy =21mv2−91×21mv2

=21mv2(1−91)

=98×21×mv2

=98× Initial kinetic energy.