With what velocity must a lead bullet at `50^(@)C` strike against an obstacle in order that the heat produced by the arrest of the motion, is sufficient of melt it, assuming that all the heat produced remains within the bullet?
(Specific heat capacity of lead `=31cal kg^(-1)K^(-1)`, melting point of lead `=335^(@)C`, specific latent heat capacity of lead `=5370 cal kg^(-1)K^(-1)` and `J=4.2` joules `cal^(-1)`)

Answer

`345ms^(-1)`