if i shout a gun in orbit in a space ship

[Silvercrest]

Re: if i shoot a gun in orbit in a space ship

Remember, the force is applied two ways. You aren't anchored to the Earth so the recoil force will alter your orbit as well.

Of course I remember something as elementary as Newton's Third Law. However, I also remember Newton's Second Law, F = ma. The mass of a typical bullet is maybe around 10 grams. The mass of a typical person in a spacesuit might be somewhere around 100 kilograms. Therefore, the acceleration imparted to the person shooting the gun is going to be about 1/10000 the acceleration imparted to the bullet, so its effect would be trivial in comparison. It would introduce a slight perturbation in your orbit, but nothing significant enough to be worth mentioning.

I had that in mind as a science-fiction story. Someone is stranded in a bad orbit, but happens to have an old handgun and a supply of ammunition. How much it could alter your orbit depends on how much ammo and time you have.

You couldn't alter it by very much in any case. Going by the figures above, and assuming that the ratio of final velocities is proportional to the ratio of accelerations, firing one bullet might impart a delta-vee of a few cm/s. So if you have, say, 20 rounds, you might be able to change your velocity by around half a meter per second or so. So if you were drifting away from your spaceship at a relatively slow rate, then maybe it could make a difference -- though you'd have to understand orbital mechanics well enough to know the right direction to fire in, since it's counterintuitive. But if you're talking about making a substantial change in your orbit, that's not in the cards.

Just remember to save one bullet in case it doesn't work.

 

[Chaos Descending]

Re: if i shoot a gun in orbit in a space ship

"Change to your delta-v" is kind of redundant in this case. Delta is the mathematical symbol for rate of change, so delta-v means change in velocity, i.e. acceleration. Firing a gun or other reaction thruster would impart delta-v.

Thereby changing your current Delta-V, which would be assumed to be zero at the start.

In short, nothing you just said makes the phrase, "change to your delta-v" redundant. Rate of acceleration can also accelerate, ya know.

 

[Christopher]

Re: if i shoot a gun in orbit in a space ship

^But phrasing it that way makes it sound as if you don't know what "delta" means.

 

[Chaos Descending]

Re: if i shoot a gun in orbit in a space ship

^But phrasing it that way makes it sound as if you don't know what "delta" means.

I can see why you might see it that way.

 

[Brolan]

Re: if i shoot a gun in orbit in a space ship

Remember, the force is applied two ways. You aren't anchored to the Earth so the recoil force will alter your orbit as well.

Of course I remember something as elementary as Newton's Third Law. However, I also remember Newton's Second Law, F = ma. The mass of a typical bullet is maybe around 10 grams. The mass of a typical person in a spacesuit might be somewhere around 100 kilograms. Therefore, the acceleration imparted to the person shooting the gun is going to be about 1/10000 the acceleration imparted to the bullet, so its effect would be trivial in comparison. It would introduce a slight perturbation in your orbit, but nothing significant enough to be worth mentioning.

I had that in mind as a science-fiction story. Someone is stranded in a bad orbit, but happens to have an old handgun and a supply of ammunition. How much it could alter your orbit depends on how much ammo and time you have.

You couldn't alter it by very much in any case. Going by the figures above, and assuming that the ratio of final velocities is proportional to the ratio of accelerations, firing one bullet might impart a delta-vee of a few cm/s. So if you have, say, 20 rounds, you might be able to change your velocity by around half a meter per second or so. So if you were drifting away from your spaceship at a relatively slow rate, then maybe it could make a difference -- though you'd have to understand orbital mechanics well enough to know the right direction to fire in, since it's counterintuitive. But if you're talking about making a substantial change in your orbit, that's not in the cards.

Just remember to save one bullet in case it doesn't work.

That is actually a good idea.