Question

Calculate the decrease in the kinetic energy of a moving body if it's velocity reduces to one third of the initial velocity

Answer 1

let the initial velocity of the body = v
now kinetic energy = 1/2 m v^2
k.energy = 1/2 m v^2

Now reduced velocity is Vredu = 1/3 v

Now kinetic energy = 1/2 m Vredu^2

= 1/2 m 1/9 v^2
Kredu = 1/9 k. energy

so now reduced kinetic energy = 1/9 of the kinetic energy before