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?

Answers

bobpursley
For speed, it is correct. If it were asking for velocity, I would add a negative sign, meaning the opposite direction from the bullet.
June
I've tried that, but the program I'm using still says that that is incorrect.
bobpursley
The program is incorrect. Put a hex on it.
tim
is there .136kg for 13.6g.....check that
alex
13.6g is 0.0136kg
Anonymous
2.09m/s

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