Need some OCUK knowledge

tres

tres

tres

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I've got a bet with a friend - a .22 pellet will travel:

1) 1km fired nearly horizontally
2) 1km fired straight up

Assuming a muzzle velocity of 350m/s, does anyone have the ability to work out whether i'm up 5 pints of Guinness, or owe?
 
The vertical one is the main bet - the horizontal'ly one is just to see if the pellet could make it without such a direct gravitational fight. Perhaps aimed 45 degrees above horizontal.
 
I'm currently trying to work this out ... damn mechanics :(

I don't think either are valid. Air resistance is too strong for such a light pellet.

Edit: Do a bit of googling and play around with some ballistics calculators if you are serious about this. There are a lot of other variables though. I'm off to bed, so no time.

Check out this site: http://www.hornady.com/ballistics-resource/external
 
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I know that if you drop a bullet out of your hand and fire said bullet out of a gun from the same height, they'll both hit the ground at the same time. Doesn't help I know, but an interesting fact from QI nonetheless.
 
A .22 would struggle to fire more than a few hundred metres horizontally, in fact even at an angle.

[FONT=****l]For example let's take our XS78 Co2 air rifle, this is a powerful air gun producing approximately 10.5ftlbs of energy regardless of the calibre, so the .22 (5.5mm) pellet may travel at say 500-600 feet per second[/FONT]
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If your firing from head high, that's going to take a max of about 2 seconds to hit the floor. 1500 feet max, and that being generous. That about 400 metres.
 
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There would be lots of factors involved in this. Hypothetically or what? In the absence of any negative wind it, it would go substantially further than normal conditions. Also whats the shape of the pellet, the quality of the rifling etc.
 
ChroniC said:
A .22 would struggle to fire more than a few hundred metres horizontally, in fact even at an angle.



If your firing from head high, that's going to take a max of about 2 seconds to hit the floor. 1500 feet max, and that being generous. That about 400 metres.
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Depends on the .22, I have one here that was once a little bit over powered shall we say, might have done it lol. :o
 
I'd agree... pointed at the horizon at 400m the projectile would have dropped ~6 feet and theres no way you'd get 1km straight up vertical.
 
Russinating said:
I know that if you drop a bullet out of your hand and fire said bullet out of a gun from the same height, they'll both hit the ground at the same time. Doesn't help I know, but an interesting fact from QI nonetheless.
Click to expand...

Wait, what? Maybe if from a great enough height, but from 10m give or take, the dropped pellet will only have mavity acting on it, but the fired round is going to have mavity and the energy from the shot behind it and surely will hit the ground first?
 
Swi1ch said:
Wait, what? Maybe if from a great enough height, but from 10m give or take, the dropped pellet will only have mavity acting on it, but the fired round is going to have mavity and the energy from the shot behind it and surely will hit the ground first?
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The shot from the gun is fired horizontally.....


But for the OP the question doesn't really make sense.. Define 'travel 1km' ? The pellet fired up the way will 'travel' a greater distance, but the pellet fired horizontally will end up further away.
 
Swi1ch said:
Wait, what? Maybe if from a great enough height, but from 10m give or take, the dropped pellet will only have mavity acting on it, but the fired round is going to have mavity and the energy from the shot behind it and surely will hit the ground first?
Click to expand...

The pellet velocity is only in the horizontal direction though, so if you ignore any lift from the air, the only vertical force on both pellets is mavity. Oh, and to answer the OP, if you fire the pellet from about 5ft, the vertical pellet will go something ridiculous like 6km, and the horizontal one will go 200m. That was ignoring air resistance though, so the vertical one would actually be much much lower.
 
OK just looking at the vertical one - are we saying it wouldn't reach anywhere near a kilometer? Would a smaller, faster .177 pellet get any further?
 
tres said:
OK just looking at the vertical one - are we saying it wouldn't reach anywhere near a kilometer? Would a smaller, faster .177 pellet get any further?
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No those that have suggested otherwise are wrong.

If you ignore all resistance and transonic effects, the bullet fire vertically would reach an altitude of 6.24km.
Whist the one fired horizontally (assuming a shot height of 1.5m obove the ground) would only travel 193.5m before hitting the ground.

basic GCSE Physics: using v²=u²+2as and s=ut+0.5at²

I woudl have thought you'd easily get more than 1 km in altitude, but the problem is actually far more complex than it may appear. Take in to considereation that: 350m/s is above Mach 1 at s.t.p hence oblique and normal shockwaves appear; air is infact not invicid, resulting in skin drag from boundary layer formation and the bullet has a large, turbulent wake inducing realtively large form drag; the atmospheric changes between sea level and your final altitude are enough to not only change the speed of sound, but the flow regieme around the bullet and the resulting pressure gradients and drag forces. You could also consider the change in gravitiational field strength as the bullet increases its altitude.
 
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vertica said:
No those that have suggested otherwise are wrong.

If you ignore all resistance and transonic effects, the bullet fire vertically would reach an altitude of 6.24km.
Whist the one fired horizontally (assuming a shot height of 1.5m obove the ground) would only travel 193.5m before hitting the ground.

basic GCSE Physics: using v²=u²+2as and s=ut+0.5at²

You are almost certain to acheive far more than 1 km in altitude, but the problem is actually far more complex than it may appear. Take in to considereation that: 350m/s is above Mach 1 at s.t.p hence oblique and normal shockwaves appear; air is infact not invicid, resulting in skin drag from boundary layer formation and the bullet has a large, turbulent wake inducing realtively large form drag; the atmospheric changes between sea level and your final altitude are enough to not only change the speed of sound, but the flow regieme around the bullet and the resulting pressure gradients and drag forces. You could also consider the change in gravitiational field strength as the bullet increases its altitude.
Click to expand...

In the real world we have resistance which, whilst I realise you have noted, renders the GCSE physics very lightweight here.
 
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