I'm proving that the force of a bullet is not actually enough to send a person flying backwards like you see in the movies. These are the variables I have so far. I'm not sure if all of them are really necessary to solve this. distance between gun and person getting shot = 2.45 m mass of person getting shot = 104 kg barrel length (gun) = .5 m (not sure if I need this) v of bullet = 385 m/s mass of gun = 3.10 kg (Don't think I need this?) mass of person shooting gun = 85 kg (Don't think I need this either) mass of bullet = .04 kg How deep the bullet penetrates = .2 m (Another one I'm not sure I need) I know it's an inelastic collision so eventually I'll need m1v1 + m2v2 = (m1+m2) v and I should also use conservation of momentum (m1v1 + m2v2)i = (m1v1 + m2v2)f My professor left this comment on my paper: One approach might be to use the conservation of momentum of the system to determine the velocity after the inelastic collision, but then you have to work out how to translate that into distance traveled. I'm sure you all know this but when he says distance traveled he means how far back the person travels after being shot. So I first started out using conservation of momentum and did... 104kg(v2) = .04kg(385m/s) And I got v2 = .385 m/s after the collision. Doesnt sound right though. From here not quite sure what to do. Maybe use v=d/t to find the distance he traveled after getting shot? Any help is appreciated. I really need it on this on.