If the speed of a body is halved ,what will be the change in its kinetic energy??????????

plz answer

too easy one....

as we knw that

K.E_{1} = 1/2 m v_{1}^{2}

if the speed is halfed ...then.

let the new kinetic energy be K.E_{2}

and its new velocity ( v_{2}) = v_{1}/2

K.E_{2} = 1/2 m v_{22}

K.E_{2} = 1/2 m( v_{1} / 2)^{2} ( since v_{2} = v_{1} / 2 )

= 1/2 m ( v_{1}^{2} / 4 )

= 1/2 (m v_{1}^{2} ) 1 / 4

= 1/4 [ 1/2 ( m v_{1}^{2} )] ( since K.E_{1} = 1/2 mv_{1}^{2} )

K.E_{2} = 1/4 K.E_{1}

Hence , the new kinetic energy must be 1 / 4th of the previous kinetic energy.