If momentum of a body is increased by 20% then its kinetic energy increases by _______ (%) 

Let P be the initial momentum, Kinetic energy $\mathrm{K}=\frac{{\mathrm{P}}^2}{2\mathrm{m}}$

Momentum of a body is increased by   $P^1=P+\frac{20}{100}P=1.2P$

Kinetic energy of body KE ${\mathrm{K}}^{\text{'}}=\frac{{\left(1.2\mathrm{P}\right)}^2}{2\mathrm{m}}=1.44\frac{{\mathrm{P}}^2}{2\mathrm{m}}$

Percentage change in  $\mathrm{KE}=\frac{\mathrm{K}-{\mathrm{K}}^{\mathrm{\prime }}}{\mathrm{K}}\times 100=44\%$