1. The problem statement, all variables and given/known data The expanding gases that leave the muzzle of a rifle also contribute to the recoil. A .30 caliber bullet has mass 0.0072kg and a speed 0f 601 m/s relative to the muzzle when fired from a rifle that has mass 2.8 kg. The loosely held rifle recoils at a speed of 1.85 m/s relative to the earth. Find the momemtum of the propellant gases in a coordinate system attached to the earth as they leave the muzzle of the rifle.