Question

A rifle has a mass of 4.73 kg and it fires a bullet of mass 13.6 g at a muzzle speed of 829 m/s. What is the recoil speed of the rifle as the bullet leaves the gun barrel?

So far, I've got (using p for momentum) p=p, so massXchange in velocity of the bullet will will equal the massXchange in velocity of the rifle. So my work looks like:
.136kg x 829m/s = 4.73kg x v

Which gives me 23.8m/s, which is incorrect. What am I doing wrong?

Answer 1

For speed, it is correct. If it were asking for velocity, I would add a negative sign, meaning the opposite direction from the bullet.

Answer 2

I've tried that, but the program I'm using still says that that is incorrect.

Answer 3

The program is incorrect. Put a hex on it.

Answer 4

is there .136kg for 13.6g.....check that

Answer 5

13.6g is 0.0136kg

Answer 6

2.09m/s