With respect to an object shot into the air, which has a greater effect on the path of its trajectory, gravity or wind?
I would say that generally it’s gravity. Afterall, the whole reason an object’s flight path is a parabola is because of gravity. However, I can’t get anyone to agree with me. Everyone believes that wind has the greates effect. It’s my opinion that while wind has the greatest effect on accuracy, gravity has the biggest effect on the actual trajectory.
How strong of a wind would be required to make the effect of wind greater than the effect of gravity? I’m sure that question depends on size and shape, so lets assume we’re talking about rifle bullets and not ballistic missles.
What does it take for the latteral shift of a bullet cause by wind to be greater than the vertical shift caused by gravity?
Take a look at this link,
There is a ballistic calculator linked there also.
The short of it is there are too many variables to give a short answer.
If I ever go to Florida I will make it a point to get in some plinking during a hurricane.
But that doesn’t mean a 22mph wind is equivalent to the effect of gravity, right? I mean, all of that wind’s force is not applied to the bullet like gravity’s, right?
As you say, absent gravity the projectile would end up on Mars, not in the next cornfield. It’d be one hell of a wind to make a bigger difference than that.
Also, as you say, wind has the greatest UNpredictable effect, whereas at least in principle the effect of gravity can be computed to umpteen decimal places prior to firing.
Here’s a quick answer courtesy of Google:
http://www.snipercentral.com/223.htm says that for NATO 5.56 if you set your sights for 600 yards , the bullet must climb about 38 inches above the aim point on the way, topping out at about 300 yards.
And it will fall about 41" below the aim point in the next 100y getting to 700y. That’s an example of using a cartidge type out near the limits of its range.
For the same situation, the wind drift for a 10mph wind is 9" at 300y, 43" at 600y, and 62" at 700y.
I see you’re in Germany; the chart also has equivalent metric values so I’m not going to clutter with two sets of measurements.
Due to zeroing at range, the numbers aren’t directly comparable. But overall at 600y, the bullet is pulled down something more than 38" below the bore line. That effect is about equal to the effect of a 10mph wind.
Both wind drift and gravity drop get worse at longer ranges. And they get worse at different rates. So by careful choice of very close or very long ranges a quibbler could come to the opposite conclusion.
Bottom line: It’s a silly question involving comparing things which aren’t really comparable in an engineering sense. But if you want to hit your target at a decent range, consideration of wind is at least as important as consideration of gravity. Wind is just harder to estimate accurately than range, and may well differ over the flight of the bullet.
You can’t figure it that way.
First of all 9.8 M/S^2 is an acceleration, (a change in velocity), not a velocity. The effect of gravity on the bullet amounts to it’s weight. So, for the wind to have a grater effect, it would have to exert more than 135 grams of force on a 135 gram bullet. To figure this, you would need to know the cross-sectional area of the bullet, and the speed of the wind. Maybe windage tables would have this information.
Vertical travel of 38" above and then 41" below is a total of 79" of travel at 700yd, right? So gravity beats a 10mph wind by 17" at 700yd? I guess a 15-20mph wind would have gravity beat though?
I know it’s a silly semantical question about gravity v wind. But it was a strangly worded question on a test recently. Basically asked which had the greatest effect on the path a bullet travels. Among the answer options was gravity and wind.
Figuring this was a trick question, I chose gravity. Afterall, gravity does have the greatest effect, just a very predictable one. But I suppose there is a wind speed at which the wind has a greater effect than gravity. I’m curious as to what that speed is.
If it rises 38" above line-of-sight and then falls back down to this, that’s a total of 76".
But it’s actually worse than that. Suppose I toss an object into the air so it travels 4 ft vertically, then falls back into my hand; total time in the air is a second. If I’d simply dropped the object, it would have fallen 16 ft in that second.
Likewise, 38" above, then back down to line-of-sight, then 41" below.
And it would take a considerable wind to do this. For a thought experiment, consider the vertical velocity necessary to support a bullet in mid-air.
As an aside, a 135-gram bullet would be a serious monster. Nato 5.56mm rounds have bullets around 4 gm (60-odd grains). The huge 50BMG runs around 45 gm.
If you toss an object at 16 ft/s, then it would do as you describe: rise 4 ft and fall back 4 ft in one second. But if there had been no gravity, the object would have ended up 16 ft above you. So really, the effect of gravity is that it moved the object 16 ft in one second. Exactly the same as if you’d just dropped it, or thrown it downwards, or thrown it up at 1600 ft/s.
This is best illustrated in the “Monkey and the Hunter” thought experiment: a hunter aims directly at a monkey in a tree, and the monkey drops from the tree the instant the gun goes off. Gravity accelerates both the monkey and the bullet downward at the same acceleration. The result is that the bullet always hits the monkey regardless of distance, angle, etc - as long as the gun was aimed directly at the monkey.
Obligatory nitpick (hey, it’s SDMB, that’s what we do) - only if monkey isn’t fuzzy enough to have significant air resistance that slows her fall more than fall of the bullet.
Or there is wind strong enough to deviate monkey from her trajectory.
That was my point - that the effect of gravity is not accurately characterized by noting a bullet’s midrange height.
It illustrates the point, though I’ve always felt it fails the plausibility test. What hunter aims in anticipation of the monkey jumping the instant the bullet reaches the end of the barrel?
