A lead bullet is fired at a rigid surface. At what speed must it travel to melt on impact if its initial temperature is 25 degree centigrade and heating of the rigid surface is neglected? The melting point of lead is 327 degree centigrade. The molar heat heat of fusion of lead is 4.8kJ/mol. The molar heat capacity Cp of lead maybe taken as 29.3J/(mol.K).