[jimbobghost (OP)]

suppose two astronauts get in a gunfight in deep space; and face off at a distance of six paces (or 50 ft or so).

question 1: will the guns fire with the same power as on earth without oxygen to assist the explosiveness of the gunpowder?
question 2: without the foundation of gravity to hold them in place, would the recoil of the guns push them away from each other so that neither projectile reaches their adversary?

[Kryptid]

(1) Gunpowder contains its own oxidizing agent (potassium nitrate), so the lack of oxygen shouldn't be a problem.

(2) The recoil from the guns certainly would push each astronaut backwards, but whether or not this causes the bullets to miss will likely depend on where they were aiming. If you were holding your arm out straight, then the recoil would act above your center of mass and cause you to spin. If the other person was aiming at your head, this spin might be sufficient to push your head out of the way before the bullet reaches you. The bullet would be much more likely to hit if the target was your center of mass.

[evan_au]

An astronaut has more mass (mass M) than a bullet (mass m).
- The bullet travels faster (velocity V) than the astronaut (velocity v).
- By conservation of momentum, Mv = mV.

I haven't weighed any bullets recently, but I understand that 20 grams might be possible (I'm not sure if this includes the casing).

A astronaut with mass 100kg (in his spacesuit) has 5,000 times the mass of the bullet.
So the bullet will travel 5,000 times faster than the astronaut.

The recoil will not push the astronaut away so fast that the bullet never hits the target.

[jimbobghost (OP)]

thanks for the clear explanation.

I was thinking that for every action is an equal and opposite reaction. I also misunderstood that even in deep space, mass counts; even without gravity holding it in place.