1. The problem statement, all variables and given/known data A gun of mass 500Kg fires a shell of mass 2Kg with a muzzle velocity of 500m/s. Calculate: i) the velocity of recoil of the gun ii) the force required to stop the gun in a distance of 0.25m 2. Relevant equations 3. The attempt at a solution i)I got the velocity of the gun by using the principal of conservation of momentum: (500)(0) + (2)(0) = 500v + (500)(2). I got 2m/s. ii)First i used v=d/t, 2=0.25/t, I got 0.125 seconds. Then i used Force = change in momentum/time taken. I get 8000N but the book says 4000N. Im not sure what im doing wrong??