Question

9461388 HW10 Exercise 17.47 -Enhanced-with Solution Part A What must the initial speed of a lead bullet be at a temperature of 21.0 C so that the heat developed when it is trought to rest will be just sufficient to met 1? Assume that all the inial mechanical energy of the bullet is converted to heat and that no heat fiows from the bullet to its surroundings. (Typical rithes have muzzle speeds that exceed the speed of sound in air, which is 345 m/s an2

Answer 1

Heat required to melt the bullet at 21.0 degree c Q = mL where L is the latent heat of fusion of lead and its value L = 2.5 times 10^4 J kg^- 1 the initial velocity of bullet is v then we apply energy conservation 1/2 m v^2 = mL v^2 = 2L v = squareroot 2 L = squareroot 2 times 2.5 times 10^4 = squareroot 5 times 10^4 = 2.236 times 10^2 v = 223.6 m/s