posted by Jackie
A 32 kg gun is standing on a frictionless surface.
The gun fires a 55.1 g bullet with a
muzzle velocity of 320 m/s.
The positive direction is that of the bullet.
Calculate the momentum of the bullet immediately
after the gun was fired.
Answer in units of kg · m/s.
If the gun were fixed in place, all the momentum would transfer to the bullet, which would then have momentum
p = mv = .0551kg * 320m/s
But, the gun will recoil, and we have to divide that momentum into two parts. So, if the gun has velocity v, the actual ground speed of the bullet will be reduced by v (which is negative).
32v + .0551*(320+v) = 0
v = -0.55 m/s
so the bullet, moving at 319.45 m/s has momentum
p = 0.0551 * 319.45