Question

A body of mass m is moving with a velocity 5 ms-1. Its kinetic energy is 25 J. If
velocity is doubled, what is its kinetic energy?
A boy weighing 50 kg climbs un a vertical height of 100
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Answer 1

Answer:

The answer will be 100J.

Explanation:

Given;

     velocity = 5 m/s^-1;

     Kinetic energy = 25 J;

     Mass = m;

Now, kinetic energy = 1/2 * m * v^2;

Thus,                 25J  = 1/2 * m * (5) * (5);                             (i)

If velocity is doubled;

New velocity = 2 * (initial velocity) m/s^-1;

                      = 2(5) m/s^-1;

Mass is fixed.

Thus, mass = m;

Therefore, the new kinetic energy = (1/2) * m * (new velocity)^2;

                                                         = (1/2) * m * (2(5)) *  (2(5)) ;

                                                         =  (1/2) * m * (5)*(5) * 4 ;

                                                         = 25 * 4 ;    {(1/2) * m * (5)*(5) = 25J eq. (i)}

                                                         = 100J;

That's all.