Bullets falling back to earth

Yes, same velocity they went up with many cases on manslaughter have resulted damage can be nasty as the bullet may have aquired a spin or not be in line with the fall

There was a recent story about a Klan member getting killed by a bullet that was shot into the air.

Injuries, and even fatalities, from this cause are not unknown here in the US. The risk is a probabilistic one, however. How many shots are fired, what's the population density in the area -- strictly speaking the exposed population density, as there is relatively little risk to people indoors or in cars...

Al Moore

That sure doesn't sound right to me. A bullet or any other object fired into the air, let's say straight up to keep it simple, will slow until it finally stops and begins to fall back to earth. I would think the effect of gravity and wind resistance would determine the maximun velocity of the falling bullet (object), not the velocity at which it was fired upward with. The same speed would be realized as if you had simply dropped the bullet (object) at the same altitude from a hot air balloon. Feel free to correct me if I'm wrong.

JTMcC.

No, you're right. I remember reading about this issue in Popular Science's FYI section several years ago. It's called "terminal velocity", FYI ;-)

I think it said about 9 or 10 people a year die due to people firing into the sky, usually from head and shoulder injuries (really eh?).

Regards,

Robin

They seem to be quite dangerous. At least once a year, usually around the New Year celebrations, somebody gets hurt, and sometimes killed in San Jose. For some strange reason it is always San Jose as far as I can remember.

Abrasha

It would start out with a certain amount of kinetic energy, based on its mass and muzzle velocity. The kinetic energy would be converted to potential energy, minus the work done against air resistance on the way up. On the way down after vertical motion ceased, potential energy is converted into kinetic energy, again minus the energy lost due to air resistance. If there was no air resistance, like a simplified physics problem, the effect of gravity (= stored potential energy) would be determined solely by the initial velocity, and the final velocity on its return to earth would be the same as its initial velocity. In this instance, air resistance is the only loss of energy (from the standpoint of our projectile).

Yes, provided it reaches terminal velocity from that height. There was a recent, long and annoying thread on this in sci.electronics.design which I considered x-posting here.. one of the more amusing physics thought experiments was if you fired a bullet from the imaginary surface of a stationary planet with no atmosphere directly vertically (at less muzzle than escape velocity- no problem with that on Earth), it would return at exactly the same speed as it left the muzzle, in the reverse direction. Ouch.

In real conditions, if a relatively heavy bullet isn't tumbling I could see it coming back fast enough to potentially hurt someone (imagine, say, a 180 MPH pointy metal object falling on your skull). But people don't always fire them straight up, which could be worse again. There was apparently a law (called Shannon's Law) passed in Phoenix AZ due to a youth killed from a celebratory gun firing.. common in the Hispanic community.

Gunner probably has all the facts at his fingertips on this...

Best regards, Spehro Pefhany

I have actually seen this here in the US. We had a person come into the hospital a few years back who was struck on New Years. What happens is that the bullet has less energy than directly from the gun. It still has plenty of energy though to cause damage. Whereas the high energy of a direct shot tends to cause the bullet to fragment and cause an excessive amount of adjacent damage as it dissipates it energy, the lower velocity of a falling bullet can still penetrate the body ( including the skull) but the bullet tends to stay intact and the amount of adjacent damage is significantly less as there is less energy to dissipate. It may cause minor or major damage depending on where it strikes. If it hits non-critical soft tissues then extent of the injury is not significant. However, if it hits a critical structure such as a major artery or critical brain structure, the consequences can be severe. Luckily, we don't see much of that here in the US.

Barry

Nope. As soon as it leaves the barrel it's slowing down, as, AFAIK, bullets are supersonic, and I know of nothing that has a terminal speed greater than the speed of sound, at least at this size! After it reaches the apex, where its vertical speed is zero, it is now speeding up, and will slowly (exponential decay style) approach terminal speed. Donno what number that is, though.

Tim

-- "That's for the courts to decide." - Homer Simpson Website @

Ha ha. Chlorine in the gene pool again! Or, if you will, poetic justice. All klan members should be equipped with rifles that fire only straight up.

Jim

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The phrase is 'terminal velocity' and I suspect that for any modern round fired straight up, this is indeed the determining factor, so I would put my guess in line with yours. As you suggest, there are others here who truly know the answer off the top of their heads.

Jim

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by a bullet that was shot into the air.

Funny but that seems to be where most bullets end up getting fired. If I recall wasen't one of the klan members either in a tree or up on a stand and the goof with the gun wasen't aiming exactly straight up.

A bullet fired exactly straight up will finally come to 0 speed at which it will break over and start excellerating to terminal velocity. Here in the midwest we frequently have hail that exceeds the size of many bullets and fall from much greater heights and its funny how people can just walk around in it and not get killed. I think a person would be suprised how many "accidental" shooting are blamed on "I just shot the gun straight into the air" sydrome.

tim

A neighbor suddenly had a roof leak after New Year's (in Santa Monica CA) about 10 years ago, and found what he said was a .38 slug that had penetrated the tar paper on his flat roof, but not the plywood under it.

He said it looked like it had hit traveling vertical, and with it's long axis horizontal to the roof. I didn't actually see it, but hearing his account, and knowing he didn't embellish much, think it could have killed someone had it had hit them right... but feel it sure didn't have the energy of a round fired at close range.

Erik

The terminal velocities would be different, you can't compare the two. And I'm not a weather man so don't know about the "greater heights" claim. The thing is, that height really doesn't come into play once the terminal velocity for a particular object has been reached.

Lane

Anybody with a brain know that bullets don't fall back with the same velocity that they initially left the gun barrel. And anybody who has read data on such measurements has a good idea of the maximum velocity that they achieve on the downward fall. Read a book and find out what it is! Yes, people have been killed, but it is highly unlikely for a number of reasons, one being that you would have to be hit in the head and probably in the temple, in one of the eyes, or in the ear (lying flat), or in the very center of the top of the head. And if a bullet did hit in one of these vital spots, there is no guarantee that it would result in death.

The determining factor is the angle that the gun was being held at when fired. If the barrel was pointed straight up when the bullet was fired it will go up until it reaches zero velocity and then fall back down in the general area where it was fired from ( wind drift changes that). On the way back down the bullet will reach what is known as terminal velocity. Gravity will accelerate the bullet on its way back down at 32 feet per second squared IIRC. The limiting factor is wind resistance so the bullet will reach terminal velocity and go no faster. I have seen studies that estimate that speed at about 180 mph for most bullets.

If the bullet leaves the barrel at anything less than a 45 degree angle it can really be moving when it comes back to earth since it will not reach zero velocity before it starts its downward trajectory. A round like that used in an AK-47 might travel over 4 to 5 miles before coming back to earth if fired at a shallow angle and it would still be moving fast enough to be very dangerous. The bullet fired straight up would hurt like hell if it should hit you but more than likely it would not be fatal. A good reloading manual with ballistic co-efficients will give you an idea what kind of velocity can be expected under different conditions.

Dennis

Abrasha wrote: (clip) At least once a year, usually around the New Year celebrations, somebody gets hurt, and sometimes killed in San Jose. For some strange reason it is always San Jose as far as I can remember. ^^^^^^^^^^^^ The same forces which attract tornados to trailer parks attract falling bullets to San Jose. I'm going to stay away from there around midnight, Dec. 31 from now on.

Tell that to the Klansman that died from one.