Question

By how much will the kinetic energy of a body decrease its speed is one third

Answer 1

KE = 1/2 $mv^2$

v1 = v

v2 = 1/3 v

KE1 = 1/2 $mv^2$

KE2 = 1/2 $m(v/3)^2$

       = $\frac{1}{2}m\frac{v^2}{9}$

       = 1/2 $mv^2$ /9

       = KE1 /9