A gun fires a lead bullet of temperature 300 K into a wooden block. The bullet having melting temper

Question

A gun fires a lead bullet of temperature 300 K into a wooden block. The bullet having melting temperature of 600 K penetrates into the block and melts down. If the total heat required for the process is 625 J , then the mass of the bullet is $\_\_\_\_$ grams.\ (Latent heat of fusion of lead $=2.5 	imes 10^{4} \mathrm{JKg}^{-1}$ and specific heat capacity of lead $=125 \mathrm{~J} \mathrm{Kg}^{-1}$ )\

Professor PC Thomas Classes · Answer

(c) : Let ' $m$ ' be the mass of bullet.\ $	herefore \quad m s \Delta T+m L_{f}=$ Total heat\ $\Rightarrow \quad m\left(125 	imes 300+2.5 	imes 10^{4}ight)=625$\ $\Rightarrow m=\frac{625}{(37500+25000)}=\frac{625}{62500}$\ $\Rightarrow \mathrm{m}=\frac{1}{100} \mathrm{~kg}=10 \mathrm{~g}$.