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.