Question

The mass of the body is changed to one fourth of its mass. What change in its velocity will keep the kinetic energy unchanged ?

Answer 1

We know that kinetic energy(`E`) of a body of mass `m` and velocity `v` is expressed as `1/2 mv^2`

Now,if mass is changed to `1/4th` of the initial value,and to keep the kinetic energy same,if the new velocity is `v'` so,

`E = 1/2(m/4)v'^2=1/2 mv^2`

So, `v' = 2v`

So,velocity will be twice the initial.