Bullets falling back to earth

You are right that it does not matter how you get there, but the initial velocity does matter in projectile motion problems. That is the only energy the projectile has, and it will be converted into a higher potential energy until it has zero kinetic energy at the very top. Putting aside air resistance, initial velocity and elevation is all we need to determine the maximum height the projectile will reach. There are several ways the problem can be solved, but comparing energy states is probably the most intuitive.

We don't care how high it goes, we only care about it's velocity returning to earth, after coming to a theoretical stop after being fired straight up. We are talking about bullets with no energy remaining from the initial firing. I can go out in my fromt yard right now, and fire a .22 caliber, 55 grain projectile into the sky at around 2800 fps (feet per second) or over

4000 fps. Using my original criteria of the bullet flying straight up, until stopped by the force of gravity, and returning to earth via the same gravitational force, do you really believe the bullet fired from a 220 Swift or 22-250 will hit the ground at a greater speed than the one fired from a .223? Again, I was more interested in the girl sitting next to me in H.S. physics class than the math problems, but I'm still pretty sure I'm right.

JTMcC.

We aren't living in a vacume around here. I believe you are misstaken when you say a "little" slower.

JTMcC.

kinda OT.. I remember as a kid, the army surplus store had crates of little (

1-2oz?) lead teardrop shaped things with little tin fins ( bomb shape) & the guy told me they were designed to be dropped from planes.. ..and more OT..as kids we used to shoot .22s into the frozen ice at a bit of a steep angle & many times we could see the bullet coming back up out of the ice ( seemed to come back up 10-20' or so) . I guess it somehow did a reverse arc in the ice...we recovered a few deformed bullets after they rattled back onto the top of the ice. Don't remember the temp..the ice was thick ( in Alberta) ..can't remember if they were hollow point or not..

I have heard on numerous occasion that a penny thrown off the top observation tower of thr Empire State building can hit the ground with enough force to crack a 6" concrete slab. I used to believe this statement when I was a kid, but have a hard time buying it as fact now. I just can't see it being fact, and see it more of an old wives type tale. I don;t really think you could throw a penny that hard and far enough to make it reach out sufficiently to clear the lower floors stepped out structure anyhow.

When I used to work for a living,we had a hangers airconditioning unit get a bullet hole in it. It was highly unlikely someone shot the AC from a aircraft, but down the road was a pretty bad section of town and gunshots could often be heard. We figured a shot was fired in the air and it came down and went through the AC units fan blade and compressor housings top. Visit my website:

expressed are those of my wifes, I had no input whatsoever. Remove "nospam" from email addy.

Nah! It is a lot slower - physics 101 stuff indeed.

Bob Swinney

The only difference is the 4000fps bullet will go higher than the 2800 fps bullet. This will only affect the downward speed of the bullet if the max elevation is not high enough to allow the falling bullet to reach terminal velocity. The accelleration of gravity is sufficient to make a 22 caliber projectile reach terminal velocity in significantly less than the verticle distance covered by even a 2700fps projectile, I am sure.

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One factor is that the mass vs cross-sectional area was seriously better than the average bullet, thanks to the additional length, and the the stabilization of the fins, to keep the streamlined and small cross section end pointed in the direction of flight. The cross section would (approximately) define the drag, and the mass would determine the acceleration force due to gravity. So -- as long as you could keep it stabilized, the longer the dart, the higher the terminal velocity.

Given stabilization -- a one-foot length of rebar would be significantly more dangerous than a .50 cal bullet.

Out of curiosity -- what was the altitude ceiling for WW-I period aircraft? (And for the pilots, since they almost certainly did not have bottled oxygen available at that time.) IIRC, the air force wanted the WW-II period pilots to be on oxygen at 10,000 feet or higher.

Enjoy, DoN.

Well, a golf ball hit straight up (or as close to straight as is humanly possible) with a hardball bat makes a pretty good hole in a steel covered barn roof when it comes down. Now, to be fair, the roof was old and there was likely some rust damage, but it was over a cedar shake roof, so there was more than rusty tin to come through. Never found the ball.

It is from Hatcher's book that I got the 300 fps data. And contrary to all the nonsense and no fact statements here made by many, Hatcher's groups did find that bullets fired straight up did not routinely turn over but came down base first as you said; some however tumbled or came down pointy end first.

Regardless of all the nonsense stated by some here, 300 fps is pretty slow moving in the field of weapons. BBs, air pellets, sling shots, arrows, etc. can be higher than 300 fps, and all except BBs and pellets are likely much larger and to weigh more than 150 grains. A tiny thing weighing only 150 grains isn't going to do much compared to something weighing a pound. The comparison has to be made considering both speed and weight.

I like this post. Guns shouldn't be fired close to straight up in the first place unless it's a shot gun without slugs. Who cares if it will kill you or not. I say it is really close to fatal. We tryed this once with arrows , from bird and target arrows with plain bows to compound bows and hunting arrows. I don't remember them sticking in the soft feild that far , but you don't want to catch one! It was quite interesting how they would stall out and fall over and then shake as they lined up to their own characteristic terminal velocity. I can guaranty everyone of group was very attentive of the arrow's location. We stopped after the first person lost site of it and was pushed out of the way by another and it stuck right where he was ! My main worry was running into someone else that was going the wrong direction . The closest we got was about 1.5' from the cow pie which was home base. It's hard to tell , but I would guess they went up 800 to 1,000' . They don't weigh that much and have feathers/plastic to slow them down , but I would'nt want to be hit with one , even with a pencil eraser on it.

You might be surprised about how low the terminal speed would be, but without any data there is no point in speculation. You did say the they were several inches long so they would weight much more than a bullet and with a point they could possibly have penetrated a helmet. In comparison, it is highly unlikely that a 150 grain bullet traveling at 300 fps would penetrate a helmet, just a dent. Weight is everything at low speeds, an arrow shot into the sky and falling down could penetrate you because of it's much greater weight.

Most of those were actually steel. The name escapes me..something Dog..but they were used as antipersonel devices against factories and such. Kick out several tons of those killer bees over a manned factory..and they would wreck havoc both on the machinery and the personel. Very aerodynamic, hardened steel IRRC... terminal ballistics quite high and the kinetic energy was very potent with that much drop weight.

The modern cluster bomb has its roots in these bomblets

Gunner

" ..The world has gone crazy. Guess I'm showing my age... I think it dates from when we started looking at virtues as funny. It's embarrassing to speak of honor, integrity, bravery, patriotism, 'doing the right thing', charity, fairness. You have Seinfeld making cowardice an acceptable choice; our politicians changing positions of honor with every poll; we laugh at servicemen and patriotic fervor; we accept corruption in our police and bias in our judges; we kill our children, and wonder why they have no respect for Life. We deny children their childhood and innocence- and then we denigrate being a Man, as opposed to a 'person'. We *assume* that anyone with a weapon will use it against his fellowman- if only he has the chance. Nah; in our agitation to keep the State out of the church business, we've destroyed our value system and replaced it with *nothing*. Turns my stomach- " Chas , rec.knives

Reminds me of those toy 'Lawn Dart' things? I think a few people were hurt & killed by them before they were pulled off the market.

Erik

It would be hard to tell, because a rifle bullet is not going to be spin stableized any more. It would start falling base to earth until the wind resistance hitting the flat base would start it tumbling. Now if the bullet shape had the center of gravity foward of the tip to base center point, then it would fall stable pointy end down and have a very high terminal velocity

Other posts may have said this, , please pardon my not wading thru them all.

A bullet fired at a high angle will reach whatever altitude it reaches, at which point it will be become a vertically-stationary object. Events thenceforth are no different than dropping said object from that height.

It will then fall, accelerated by gravity until its weight equals aerodynamic drag. That speed is terminal velocity that depends entirely on shape and weight, not at all on initial muzzle velocity.

Think lead raindrops. Cannon balls fall faster than bird shot regardless of muzzle velocity that put them at altitude.

A falling 7.62mm or 30.06 bullet would dent your helmet but probably not punch it, a falling 155 mm dud round surely would.

I was told that they were called Crazy Dogs.

The ones I saw at gun shows were made of hard lead with sheet metal fins.

I think that the original cluster bombs were bunches of small anti personal ' butterfly ' bombs packed in a canister, and dropped by the Germans in WW2.

Greg H.

Which brings to mind a story about a party, the neighbors Pekinese (sp?) a tall fence and a miss thrown lawn dart. Not for the squeemish.

Gunner

" ..The world has gone crazy. Guess I'm showing my age... I think it dates from when we started looking at virtues as funny. It's embarrassing to speak of honor, integrity, bravery, patriotism, 'doing the right thing', charity, fairness. You have Seinfeld making cowardice an acceptable choice; our politicians changing positions of honor with every poll; we laugh at servicemen and patriotic fervor; we accept corruption in our police and bias in our judges; we kill our children, and wonder why they have no respect for Life. We deny children their childhood and innocence- and then we denigrate being a Man, as opposed to a 'person'. We *assume* that anyone with a weapon will use it against his fellowman- if only he has the chance. Nah; in our agitation to keep the State out of the church business, we've destroyed our value system and replaced it with *nothing*. Turns my stomach- " Chas , rec.knives