A 20gram lead bullet at 30 degreecentregrate moving at 350m/s embeds itself in a wooden block.if 70% of the _?

Question

initial K.E becomes internal energy of the bullet.what is the final temperature.

Answer 1

The initial energy of the bullet is 0.5*m*v^2. 70% is converted to heat, so the energy into the bullet is 0.7*0.5*m*v^2 = 857.5 J. Now look up the specific heat of lead: 26.65 J / mole ºK. The atomic mass of lead is 207.2, so 20 grams is 20/207.2 = 0.0965 moles. The heat energy is given by

E = cp *n*∆T. The temp rise ∆T is then E/(cp*n)

∆T = 333.3º, so the final temp is 363.3ºC