1. The problem statement, all variables and given/known data A bullet m= 9.0 g leaves the barrel of a rifle with a speed = 8.0 x 10 ^2 ms-1 (by the may im sure - is this 80 ms-1 ?) The mass of the rifle = 1.8 kg The rifle is free to move back Calculate the speed of recoil 2. Relevant equations I figured I would need these : p=mv F=mv/t I'm not sure wether that's all I need. 3. The attempt at a solution Well, first of all I think that the momentum 1 way = the momentum the other way. so p1=p2 m1 x v1 = m2 x v2 9 [g] x 80 [ms-1] = 1800 g (1.8 kg right ?) x V2 720 = 1800 V2 V2= 720/1800 V2= 0.4 Is this correct guys ?