# Recoil velocity of a cannon

1. Oct 27, 2016

### Luke0034

1. The problem statement, all variables and given/known data
A 1000 kg cannon shoots a 30 kg shell at an angle of 25 degrees above the horizontal and a speed of 500 m/s with respect to the ground. What is the recoil velocity of the cannon?

2. Relevant equations
Not sure

3. The attempt at a solution
I really don't know where to begin. The chapter that this problem is in deals with center of mass, but I'm not sure how to apply that to this problem. My teacher also never taught us about recoil velocity either, so I'm pretty lost and could really use a step-by-step explanation, rather than just an answer. Thanks guys, btw I'm new here, so let me know if I didn't post this correctly or something.

2. Oct 27, 2016

### Staff: Mentor

You could start with a drawing where you insert all the data you have, especially the momenta and the directions in which they point.
You have a shell and a cannon, their masses, one speed known and one unknown and you may assume that the ground on which it stands is horizontal. Hint: the momenta are vectors.

3. Oct 29, 2016

### CWatters

Have you studied conservation of..

4. Oct 29, 2016

### Luke0034

Nvm guys. I got the answer easily after I figured out it had nothing to do with center of mass, and when I figured out what recoil velocity was. I thought it was asking for how fast the barrel of the gun would fly back, but it was talking about how fast the whole tank would move backwards... easy.