Let $m_1$ and $m_2$ be the mass of light and heavy bodies respectively, i.e. $m_2>m_1$

$\frac{m_2}{m_1}>1$ ...(i)

$K_1$ and $K_2$ be the kinetic energy of light and heavy bodies respectively, then

$K_1=\frac{p^2}{2m_1}$ and $K_2=\frac{p^2}{2m_2}$ , [where $p=$ momentum]

$\therefore \frac{K_1}{K_2}=\frac{p^2/2m_1}{p^2/2m_2}=\frac{m_2}{m_1}$

$\frac{K_1}{K_2}=\frac{m_2}{m_1}$

But $\frac{m_2}{m_1}>1$ , From Equation. (i),

$\therefore \frac{K_1}{K_2}>1$

$K_1>K_2$

i.e. Light body has greater kinetic energy.