Question

Calculate the change in the Kinetic energy of a moving body if its velocity is reduced to 1/3rd of the initial velocity.

Answer 1

Let the inital kinetic energy be E₁=E

Now, the kinetic energy is directly proportional to the square of the velocity 

K.E ∝ v₂

∴ Final kinetic energy =E₂=`1/9E`

Hence, the change in kinetic energy is given as,

`ΔE=E_1-E_2`

`Delta E=E-1/9E`

`Delta E=8/9E`