It has been said that sometimes lead bullets melt upon impact. Assume that a bul

Question

                    It has been said that sometimes lead bullets melt upon impact. Assume that a bullet with an initial temperature of 3.00*102K receives 62.9% of the work done on it by a wall on impact as an                     increase in internal energy.
                    
                    a) What is the minimum speed with which a 14.9g lead bullet would have to hit a surface (assuming the bullet stops completely and all the kinetic energy                     is absorbed by it) in order to begin melting?                 

                    b) What is the minimum impact speed required for the bullet to melt completely?                 

Explanation / Answer

a) melting point is 327.5 C

Q = mc dT

0.629*0.5*m*v^2 = m*128*(327.5+273.15-300)

v=349.8 m/s

b) to fully melt

0.629*0.5*m*v^2 = m*128*(327.5+273.15-300)+ m*23.0E3

v=442.1 m/s

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