[ARCHIVED THREAD] - Ballistics/Physics Question (Page 1 of 3)
Posted: 1/21/2011 5:52:32 AM EDT
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If you were to take 10 different rifle and pistol calibers and line them all up on the same bench, in the same type of mount with zero/no elevation and fire them all at the same time, would each and every bullet hit the ground at the exact same moment? Poll incoming. |
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In general, no.
If they were all set at an elevation of zero degrees, I think they would. But, in general, no. The faster calibers will impact later than the slower calibers with a positive elevation; the faster calibers will impact sooner than the slower calibers with negative elevation. ETA: this is assuming no atmospheric / weather interferences, that is, the test is done in a vacuum. |
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Quoted: If there was no elevation then the answer would be yes. Anything other than perfectly level and the answer is no. The way you worded your question the answer is no. I apologize for that and have edited the question. Thanks for the save. I meant zero elevation. |
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Quoted: You have different calibers. They will have different powder charges behind them. They will achieve different heights. So even though they'll stop when their speed equals zero and fall at the same rate (in a vacuum) they'll all land at different times. A bullet does not rise when shot out of a barrel. |
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Strictly, no. The farther a round travels, the more the curvature of the Earth drops away from it. So even a bullet moving 1fps faster has more distance to fall and will thus arrive later. It may be a fraction of a picosecond, but it is still later. If the elevation of the guns is more than 00 the faster moving bullets will have more vertical speed value and will take longer to fall than the slower moving bullets. |
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No.
Different barrel length and different velocities will mean that the bullets exit the barrels at different times. The bullet won't start dropping until it leaves the barrel. If all bullets exited the barrels at the exact same moment, then I am guessing all bullets would hit the ground at the exact same moment. |
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Quoted:
Quoted:
You have different calibers. They will have different powder charges behind them. They will achieve different heights. So even though they'll stop when their speed equals zero and fall at the same rate (in a vacuum) they'll all land at different times. A bullet does not rise when shot out of a barrel. The op was edited. It the original post the guns were set to the same elevation not set to no elevation. |
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Apparently some people in this thread did not have a good science teacher when they were growing up.
Feather and BB in a vacuum tube both fall at exactly the same rate. In your example the only difference in the rate of drop of the bullets is that they have very SLIGHT difference in air resistance, otherwise they fall at exacty the same rate regardless of how fast or how far forward they travel (unless they are in a vacuum as above). ETA: based on some of the responses I would agree that yes they would all have to leave the barrel at exactly the same time, and the "range" would have to be perfectly flat (but I'm not good enough at physics to understand whether or not the curvature of the earth would affect it). |
| There are too many variables in the question. If the bullets left the barrels at the same time, the ground would have to be perfectly level out to the distance the fastest round would travel, Ect. In the real world you would never be able to achive the ideal conditions to get every bullet to land at the same time. The difference in time would be very small however and depending on how many significant figures were used would most likely be very close to zero difference. |
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Quoted: You have different calibers. They will have different powder charges behind them. They will achieve different heights. So even though they'll stop when their speed equals zero and fall at the same rate (in a vacuum) they'll all land at different times. +1 |
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in a vacuum, yes they would hit the ground at the same time. Even though are all falling at 9.8m/sec^2, aerodynamics do come into play (slightly) as well as the rate of spin and direction. remove the atmosphere, and all would hit the ground at the same time. They would travel different distances before doing so, based on the velocity of the round as it left the barrel.
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Quoted:
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If there was no elevation then the answer would be yes. Anything other than perfectly level and the answer is no. The way you worded your question the answer is no. I apologize for that and have edited the question. Thanks for the save. I meant zero elevation. Then, in theory, yes they'd all strike the ground at the same moment. In practice, atmospheric influences might introduce some variables which would cause impact times to differ ever so slightly. If the test were done in a total vacuum, then yes, they'd all strike the ground at the same moment. ETA: this also assumes something else. The projectiles would all have to leave the barrel of each gun at the same moment. Differing barrel lengths and the amount of time each bullet spent in its barrel would cause impact times to vary, unless all bullets left their barrels at the same moment. |
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Quoted:
Quoted:
Quoted:
You have different calibers. They will have different powder charges behind them. They will achieve different heights. So even though they'll stop when their speed equals zero and fall at the same rate (in a vacuum) they'll all land at different times. A bullet does not rise when shot out of a barrel. The op was edited. It the original post the guns were set to the same elevation not set to no elevation. Yep. 
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In the limit that the Earth's curvature is very small compared to the length of the bullets flight, yes, they will all hit the ground at the same time.
They will also hit the ground at the same time as a bullet dropped from muzzle height. ETA: I also think that the air resistance difference due to the different bullet shapes will be negligible for all practicle projectiles, since the velocity component normal to the Earth is very small and other factors (such as timing the shots to go off at once) will cause much more variation. |
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Quoted: In the limit that the Earth's curvature is very small compared to the length of the bullets flight, yes, they will all hit the ground at the same time. They will also hit the ground at the same time as a bullet dropped from muzzle height. You also paid attention in science class... |
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Assuming they are all at the same elevation to start and there are no differences in barrel angle, yes, gravity doesn't care how fast you are moving or what you mass. All bullets will hit the ground at the same time but at varying distances.
I do want to add a disclaimer. There will be a very very very minor difference between rounds due to air resistance based on the cross section of the bullets, but you would need some very fancy equipment to detect that level of difference. The other difference will be that some rounds are larger diameter than others so if you were aligning the center of each bore then the larger caliber rounds would touch first. Again, on small arms this is a minuscule difference but it does exist. Simply put, if you align the bottom of each bore and are working in a vacuum and the barrels are all FLAT (any angle throws this way off) and the ground you are shooting across is also flat and parallel to the barrels then the bullets should all impact at the same moment. |
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maybe - depends on the height and what the dynamic pressure build up is under each bullet as it drops. In atmosphere, there is a terminal velocity component. Just like a person jumping out of an airplane will accelerate until they reach terminal velocity. At that point they cannot overcome the compression of the air under them. The same will hold true for the bullets. The shape of the bullet will greatly affect this. wadcutter, boat tail, spire point, round nose, hollow point, etc. Gravity may be the law, but terminal velocity is the crazy bitch that screws it up. Quoted: Quoted: In the limit that the Earth's curvature is very small compared to the length of the bullets flight, yes, they will all hit the ground at the same time. They will also hit the ground at the same time as a bullet dropped from muzzle height. You also paid attention in science class... |
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Quoted:
There are too many variables in the question. If the bullets left the barrels at the same time, the ground would have to be perfectly level out to the distance the fastest round would travel, Ect. In the real world you would never be able to achive the ideal conditions to get every bullet to land at the same time. The difference in time would be very small however and depending on how many significant figures were used would most likely be very close to zero difference. Good point. Ground has to be perfectly level. Assuming perfectly level ground, yes, all bullets fall at the same speed. How fast they are going laterally doesn't matter. |
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Quoted: Assuming they are all at the same elevation to start and there are no differences in barrel angle, yes, gravity doesn't care how fast you are moving or what you mass. All bullets will hit the ground at the same time but at varying distances. I do want to add a disclaimer. There will be a very very very minor difference between rounds due to air resistance based on the cross section of the bullets, but you would need some very fancy equipment to detect that level of difference. The other difference will be that some rounds are larger diameter than others so if you were aligning the center of each bore then the larger caliber rounds would touch first. Again, on small arms this is a minuscule difference but it does exist. Simply put, if you align the bottom of each bore and are working in a vacuum and the barrels are all FLAT (any angle throws this way off) and the ground you are shooting across is also flat and parallel to the barrels then the bullets should all impact at the same moment. Actually it does... |
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Quoted:
maybe - depends on the height and what the dynamic pressure build up is under each bullet as it drops. In atmosphere, there is a terminal velocity component. Just like a person jumping out of an airplane will accelerate until they reach terminal velocity. At that point they cannot overcome the compression of the air under them. The same will hold true for the bullets. The shape of the bullet will greatly affect this. wadcutter, boat tail, spire point, round nose, hollow point, etc. Gravity may be the law, but terminal velocity is the crazy bitch that screws it up. Quoted:
Quoted:
In the limit that the Earth's curvature is very small compared to the length of the bullets flight, yes, they will all hit the ground at the same time. They will also hit the ground at the same time as a bullet dropped from muzzle height. You also paid attention in science class... You've got to drop it from a pretty appreciable height for that to become a problem for a practical projectile. |
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Quoted:
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Assuming they are all at the same elevation to start and there are no differences in barrel angle, yes, gravity doesn't care how fast you are moving or what you mass. All bullets will hit the ground at the same time but at varying distances. I do want to add a disclaimer. There will be a very very very minor difference between rounds due to air resistance based on the cross section of the bullets, but you would need some very fancy equipment to detect that level of difference. The other difference will be that some rounds are larger diameter than others so if you were aligning the center of each bore then the larger caliber rounds would touch first. Again, on small arms this is a minuscule difference but it does exist. Simply put, if you align the bottom of each bore and are working in a vacuum and the barrels are all FLAT (any angle throws this way off) and the ground you are shooting across is also flat and parallel to the barrels then the bullets should all impact at the same moment. Actually it does... No... gravitational acceleration is constant. |
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Quoted:
Quoted:
Assuming they are all at the same elevation to start and there are no differences in barrel angle, yes, gravity doesn't care how fast you are moving or what you mass. All bullets will hit the ground at the same time but at varying distances. I do want to add a disclaimer. There will be a very very very minor difference between rounds due to air resistance based on the cross section of the bullets, but you would need some very fancy equipment to detect that level of difference. The other difference will be that some rounds are larger diameter than others so if you were aligning the center of each bore then the larger caliber rounds would touch first. Again, on small arms this is a minuscule difference but it does exist. Simply put, if you align the bottom of each bore and are working in a vacuum and the barrels are all FLAT (any angle throws this way off) and the ground you are shooting across is also flat and parallel to the barrels then the bullets should all impact at the same moment. Actually it does... Both gravitational force and momentum scale linearly with rest mass for non-relativistic particles. |