A lead bullet penetrates into a solid object and melts. Assuming that 40 % of its kinetic energy is used to heat it, the initial speed of bullet is:…

A lead bullet penetrates into a solid object and melts. Assuming that $\displaystyle 40 \%$ of its kinetic energy is used to heat it, the initial speed of bullet is : (Given, initial temperature of the bullet $\displaystyle =127^{\circ} \mathrm{C}$, Melting point of the bullet = $\displaystyle 327$°C, Latent heat of fusion of lead $\displaystyle =2.5 \times 10^4 \mathrm{~J} \mathrm{~kg}^{-1}$, Specific heat capacity of lead $\displaystyle =125 \mathrm{~J} / \mathrm{kg} \mathrm{K}$ )