My father reports a cousin who inexplicably fell to the ground, dead, while putting up hay. This was in an open field in Montana, almost 60 years ago.
Upon examination, the dead boy was determined to have a small hole in the top of his head. An autopsy revealed a .22 caliber bullet. No one in the haying party heard a gunshot, nor was anyone from the ranch hunting.
I immediately thought of this incident when I read this column. Now that there’s a convenient method for feedback, I decided to share it.
I was in a convention in Chicago several years ago when a speaker told a story of a well known politician (can’t remember who) as a youth shot a gun into the air, and the bullet fell and struck and killed another kid, the event was seen by the locals as a tragedy for both families, the act was not seen as a criminal act.
As opposed to the 11 year old in Michigan who was tried as an adult. His defense lawyer (ok, so it was Fieger), claimed that the kid had shot into the air, not intending to hit anyone, and the bullet did fall and kill the other guy. as a side note, he DID demonstrate that the gun in question malfunctioned on a serious basis which calls into question if the kid COULD have even aimed it. anyhow.
will try and remember the politcian name and check it out…
FWIW, this is considered to be a moderately serious problem around the holidays in my hometown of Phoenix. For a while in the 90s, it seemed like there wasn’t a New Year’s Eve or 4th of July that didn’t go by without someone being injured and/or killed by a few rounds that some bozo had popped off into the night sky.
They’ve actually made bilingual public service spots that they air on TV now at appropriate times of the year…“Remember - falling bullets can kill,” intones a serious-sounding announcer. What a news flash. :rolleyes:
Well, I’ll be…there’s even some Realvideo of the aformentioned public service announcements on that site. Though they look like newer/slicker compared to the ones I recall when I was living there
In this article, it’s mentioned that “Officials say the Iridium hardware is within government guidelines for acceptable risk: less than a one in 10,000 chance of hitting a person on the ground.” Seems like shooting a bullet in the air wold have comparable risks. So why are people allowed to drop satellites on people’s heads, but not bullets?
Well, 1 in 10,000 for someone to be hit seems awfully high. However, there's more going on here. The satellites *ARE* going to come down sometime. A controlled re-entry is more likely to be safe than an uncontrolled one. Furthermore, leaving them in orbit is also a risk--they might hit something else, maybe even something manned.
I read this in a book that was an account of a helicopter pilot’s experiences in the Vietnam war. During the New Year’s celebrations, the soldiers fired their weapons into the air as the new year started, apparrently with no casualties.
If you fire a bullet into the air the velocity time graph (ignoring air resistance) is parabolic this basically means the Kinetic energy used for the Bullet to reach a height is converted into Gravitational Potential Energy.
At the bullets highest point the bullets potential energy equals the Kinetic energy (when the bullet was first fired) + the heat and sound energy lost by the air friction. So on the bullets way down it will accelerate, changing the GPE back into KE. It once again looses alot to heat caused by friction, but gains it’s velocity again.
The total losses in the bullets velocity are very near 40% caused by mainly energy loss to heat… But the bullet still has enough velocity and momentum to strike someone from above and kill them.
However unlikely that the bullet would actually hit someone you can be sure that if it did hit they wouldn’t be alive for long.
It’s really going to depend on the bullet’s mass and profile. All bullets fired into the air will reach terminal velocity on the way down. What that velocity will be depends on the bullet’s mass and profile.
Because of this, I doubt that a .22 bullet would kill you - it’s just not heavy enough. A bigger caliber bullet could, though.
Im sorry Perfect dark but you are talking total bollocks. You think ‘oh yeah, i can just spout some physics crap and get away with it’
Firstly you say that friction will slow down the bullet, but you say at the beginning that you are ignoring ‘air resistance’ which is the same thing.
You are partially right though, If you fire in the air, the bullet will theoretically come down at the same speed, without air resistance, but with air resistance taken into account, the bullet might not come down at the same speed as the explosion of gunpowder gives a much greater acceleration and force than gravity.
Nukeman, it doesn’t matter that gravity is lower acceleration than the blast of gunpowder. For purposes of the situation, consider the blast of gunpowder to be “instantaneous”, or the length of time in the barrel. After that, it is giving no more push. So you set up a situation with an initial velocity straight up, constant acceleration straight down. The bullet goes up to the apex, slows to a stop, and starts falling. It reaches the same downward velocity as it initially had to go up.
Then you add air friction and coriolis and the fact the gun was not quite pointed straight up. Now the air slows the bullet a little more than just gravity on the way up, and then on the way down the bullet reaches terminal velocity and cannot accelerate any more. The angle of the barrel points it a little off to the side, coriolis kicks in and the bullet’s path curves, and the wind blows and makes it drift.
PerfectDark may have been less than clear, but he was mentioning the ideal case ignoring air resistance to show that behavior, then adding air resistance and discussing how it affected the outcome. Sort of like I did.
The only problem with that (and what makes it confusing), is that when you add in air resistance, the behaviour of the bullet bears absolutely no relation to what it would do without air resistance. There’s really no point in making the original no-air case, because it’s completely irrelevant.
The vast limiting characteristic on the downward velocity of the bullet is its terminal velocity, and it probably reaches that within the first few hundred feet of the drop. So it doesn’t matter if you shoot the bullet up 500 feet or 5 miles. It’s still coming down at terminal velocity.
Well I am sorry that I didn’t make it quite clear why I said without air resistance and then went on to put air resistance in.
Aristotle argued that once a projectile ran out of impetus it would fall vertically from the sky. In 1638 Galileo argued that this was wrong, the trajectory would be parabolic. Galileo would have been right if there was no air resistance. Aristotle was almost right but for the wrong reasons. At low air speeds air resistance is neglible. But at greater speeds it becomes considerable. For instance trial-and-error has shown that the maximum range for a bullet fired in air is achieved at an elevation of 33°, a rough rule-of-thumb that works for most guns. As a crude approximation, the angle of decent is 2½ times the angle of launch, so for a 33° elevation of fire, the bullet will arrive at 82.5°, or very near verticle. Any greater elevation of the gun merely means that the bullet will drop vertically and the last part of the flight will add nothing to the range. So the war veterans were right, bullets did fall on them vertically from the sky.
Typically, the bullet exits the muzzle at about 800 m s-1, spinning at some 3000 revolutions per second. At first, it goes off with a slight wobble, which straightens out after about 100m, whereon it settles down to the main part of it’s flight, nose first spinning steadily. In the last part of the bullets flight, the final slowing occurs and the bullet drops out of the sky. The spinning tries to keep the bullet pointing straight ahead but as it falls toward earth, the bullet cuts through the air sideways and the air resistance becomes great. The bullet begins to tumble end-over-end, it tears apart what ever it hits.
So there, the bullet does fall vertically and it is quite lethal.
Sorry your’e probably right Irishman, but I imagine that the instant acceleration of the bullet fired from a gun would be different from the much slower acceleration of the bullet due to gravity when it would have a constant force on it from gravity. It would depend on how high the bullet got before it started to come down again and also on how long it takes for a bullet to reach its terminal velocity.
NB With bullets it is very important to take into account air resistance. If you stood on the moon and fired a bullet (slow enough not to have an escape velocity) it would travel around the moon and hit you in the back.
eg if a bullet is fired downwards from any height, it will kill someone because of the almost instant acceleration, but a bullet would have to drop from a large enough height to reach terminal velocity before it could kill someone.
Also, how do we know that the bullet’s terminal velocity is enough to kill someone? When a bullet is fired from a gun horisontally, it might travel faster than its terminal velocity, and from a large enough distance, the bullet might not have enough power to kill someone due to slowing down from air resistance, and because a falling bullet never goes faster than the terminal velocity, it might not kill someone, though this depends on the caliber of the bullet, as a larger bullet would have almost the same air resistance (and therefore the same terminal velocity) but a greater momentum and therefore a greater force upon impact.
The conclusion seemed to be that most bullets would not go into an orbit (or at least, not an orbit that wouldn’t intersect the surface), but that it wouldn’t be too difficult to find/build a gun that could do it.
PerfectDark, while you gave a lot of good detail, the topic of the column was shooting straight up in the air, not shooting for range. Let’s all be on the same page.
Nukeman, regarding acceleration of the gun vs acceleration of gravity, while they have very different magnitudes, they have very different durations as well. Yes the force from the propellant in the gun acts quick and hard to give the bullet a lot of energy and momentum. Yes the force of gravity works slowly and lightly to slow the bullet down, and then pull it back to the Earth. But the two cancel out, because you are putting them essentially in direct opposition. (Again that is the ideal no air resistance case, ignoring coriolis, blah blah blah). The force to go up is imparted “instantaneously” and then it is over. The force of gravity starts as soon as the bullet leaves the barrel, and lasts till it hits the ground again. Gravity slows the bullet, then makes it fall down again.
But the real life case has to include air resistance, up and down, so it slows more quickly than just gravity, and it only regains speed back to the terminal velocity.
Otherwise I think we are generally understanding the same issues. How much energy the bullet has when it returns to the ground depends on how far it falls, and what it’s terminal velocity is. Size and shape play a factor in terminal velocity.