Question

A bullet with a mass of 5.00* 10^ -3 kg is loaded into a gun. The loaded gun has a mass of .52 kg. The bullet is fired, causing the empty gun to recoil at a speed of 2.1 m/s. What is the speed of the bullet?

ok i worked it out and get 218.4 but that answer does not appear in the answer choices! did i do something wrong or is the teacher wrong??
plz plz plz help!!

Answer 1

.005*V = (0.52-.005)*2.1
V = 216.3 m/s
There is a 1% difference from your answer because you did not subtract the mass of the bullet from that of the loaded gun. You were correct to use the law of conservation of momentum

Answer 2

She rounded to 2 sig figs