Question

A bullet with a mass of 5.00 x 10^-3 kg is loaded into a gun. The loaded gun has a mass of 0.52 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?

Answer 1

You can use conservation of momentum
\[p_i = p_f\]
noting that for each object in the problem
\[p=mv\]
Initial momentum is zero, and there are two terms for final momentum of the system - one for the bullet, and one for the empty gun (note that the problem only gives you the mass of the *loaded* gun, so you have to find the mass of the gun without a bullet in it). The unknown that you solve for is the velocity of the bullet.

Answer 2

220 m/s
mass of the bullet * velocity of the bullet = mass of the gun * velocity of the gun
0.005 kg * v = 0.52 kg * 2.1 m/s
-> v = (0.52kg * 2.1 m/s) / 0.005 kg = 218.4 m/s

Answer 3

Remember both that we're looking for the velocity of the bullet, and that the mass of the gun is actually
\[m_{gun} = .515kg\]
when the bullet has left the chamber. The gun did indeed recoil with a velocity of 2.1m/s, so the velocity of the bullet should be much higher.
\[v_{bullet} = \frac{m_{gun} v_{gun}}{m_{bullet}} = \frac{(.515kg)(2.1m/s)}{.005kg} = 216 m/s\]

Answer 4

oh yea, @AllTehMaffs is right, hehehe. My bad, I am terribly sorry @lillybye

Answer 5

let me take off my stupid comments, hehehehe . Again, I apology @lillybae