Question

A body of mass 5 kg is moving with a velocity of 10 ms⁻¹. What will be the ratio of its initial kinetic energy and final kinetic energy, if the mass of the body is doubled and its velocity is halved?

Answer 1

For a body of mass 5 kg:

Initial kinetic energy:

`K_i = 1/2mv_i^2`

= `1/2 xx 5 xx 10^2`

= 250 J

If the final velocity is v, then

`K_f = 1/2 xx 5 xx v^2`

Therefore,

`K_i : K_f = 10^2 : v^2`

`K_i : K_f = 100 : v^2`