Original Usenet thread from alt.ascii-art, started 26 Mar 2002.
_ _ _ _ _ _ | | | |___ ___ _ __ ___| |_ / \ _ __ ___| |__ (_)_ _____ | | | / __|/ _ \ '_ \ / _ \ __| / _ \ | '__/ __| '_ \| \ \ / / _ \ | |_| \__ \ __/ | | | __/ |_ / ___ \| | | (__| | | | |\ V / __/ \___/|___/\___|_| |_|\___|\__| /_/ \_\_| \___|_| |_|_| \_/ \___|
A question for those interested in physics...
alt.ascii-art
· 44 messages · 26 Mar 2002 - 2 Apr 2002
"Robert Bowmaker" <rob...@dse.gen.nz> wrote in news:x7Vn8.1094$sO2...@news.xtra.co.nz: > Firing bullets straight up is a common occurence in many situations > (i.e. warning shots, I would hope warning shots aren't a common occurance where you're from. ;-) > shooting at the sky during a funeral for certain > people etc.) Shooting done for a salute usually is done with blanks. > The question is: What actually happens to the bullet? Does it go into > space? Does it fall back down? Does it burn up? None of the above? It falls back down. I don't know how much harm a few onces of lead will do if it falls on you. ;-) Edwin
C Lund <chr...@NOSPAMchello.no> wrote in news:chr...@news01.chello.no: > In article <x7Vn8.1094$sO2...@news.xtra.co.nz>, > "Robert Bowmaker" <rob...@dse.gen.nz> wrote: > >> Firing bullets straight up is a common occurence in many situations >> (i.e. warning shots, shooting at the sky during a funeral for certain >> people etc.) >> >> The question is: What actually happens to the bullet? Does it go into >> space? > > Unlikely. I don't think the bullet goes fast enough. > >> Does it fall back down? > > Yes. > >> Does it burn up? > > Unfortunatly, no. > > Not only does the bullet fall back down, but when it hits the ground, > it's travelling at roughly the same speed as when it left the gun > (minus a little for air resistance). I'm pretty sure people have been > killed this way. No, the force of gravity acting on a few ounces of lead can't accelerate it to the same velocity it had by being fired out of the gun. If it could, you'd never be able to fire the bullet straight up. The forces would be equal. Edwin
In article <a7q9p0$n6or0$2...@ID-56786.news.dfncis.de>, Edwin <zer...@aiur.org> writes: >C Lund <chr...@NOSPAMchello.no> wrote in >news:chr...@news01.chello.no: > >> In article <x7Vn8.1094$sO2...@news.xtra.co.nz>, >> "Robert Bowmaker" <rob...@dse.gen.nz> wrote: >> >>> Firing bullets straight up is a common occurence in many situations >>> (i.e. warning shots, shooting at the sky during a funeral for certain >>> people etc.) >>> >>> The question is: What actually happens to the bullet? Does it go into >>> space? >> >> Unlikely. I don't think the bullet goes fast enough. >> >>> Does it fall back down? >> >> Yes. >> >>> Does it burn up? >> >> Unfortunatly, no. >> >> Not only does the bullet fall back down, but when it hits the ground, >> it's travelling at roughly the same speed as when it left the gun >> (minus a little for air resistance). I'm pretty sure people have been >> killed this way. > >No, the force of gravity acting on a few ounces of lead can't accelerate it >to the same velocity it had by being fired out of the gun. If it could, >you'd never be able to fire the bullet straight up. The forces would be >equal. > Nope, that's wrong reasoning. The force of gravity is weaker but it acts over far larger distance than the force propelling the bullet out of the barrel. In the absence of air resistance, the bullet would hit the ground at the same velocity at which it was fired up. Air resistance changes this significantly, of course. Mati Meron | "When you argue with a fool, mer...@cars.uchicago.edu | chances are he is doing just the same"
On 26 Mar 2002, Edwin wrote: > No, the force of gravity acting on a few ounces of lead can't accelerate it > to the same velocity it had by being fired out of the gun. If it could, > you'd never be able to fire the bullet straight up. The forces would be > equal. Back to Physics 101 for you. You're confusing impulse, work, and force. Here's a hint: The farther an object falls, the faster it falls. And what is going on with posting to a dozen newsgroups? No idea why the follow-up is ascii-art of all things, but hey, that's what it is. -- If you ever would give them a helping hand, You can be sure they'll chop off the arm. Never, ever, never trust a Klingon; you will always regret it.
<mer...@cars3.uchicago.edu> <...> | >> "Robert Bowmaker" | >> | >>> Firing bullets straight up is a common occurence in many situations | >>> (i.e. warning shots, shooting at the sky during a funeral for certain | >>> people etc.) <...> /\ | | | | | | | | '__' | '| '|' | || '|''
Edwin <zer...@aiur.org> wrote: >No, the force of gravity acting on a few ounces of lead can't >accelerate it to the same velocity it had by being fired out of the gun. Gravity accelerates everything equally, lead or iron, a few ounces or many tons. Surprisingly perhaps (depends on what you know), without air resistence, anything thrown vertically upwards will come down and hit the ground with the same speed. The faster the initial speed. The higher it goes before starting downwards and therefore the longer the gravity has to accelerate it: it all works out. In practice, air resistance will slow it down. -Anil
On Tue, 26 Mar 2002 20:18:10 +0000 (UTC), "Laury" <gni...@moc.tenretnitb> wrote: > ><mer...@cars3.uchicago.edu> <...> >| >> "Robert Bowmaker" >| >> >| >>> Firing bullets straight up is a common occurence in many >situations >| >>> (i.e. warning shots, shooting at the sky during a funeral >for certain >| >>> people etc.) ><...> > > > /\ >| | >| | >| | >| | >'__' >| '| > '|' >| || >'|'' where it lands nobody knows "'. ." '. .' '. .--. |'.| |.'| |'.| |.'| \ / \/ lgbeard
In article <a7q9p0$n6or0$2...@ID-56786.news.dfncis.de>, Edwin <zer...@aiur.org> wrote: > > Not only does the bullet fall back down, but when it hits the ground, > > it's travelling at roughly the same speed as when it left the gun > > (minus a little for air resistance). I'm pretty sure people have been > > killed this way. > > No, the force of gravity acting on a few ounces of lead can't accelerate it > to the same velocity it had by being fired out of the gun. If it could, > you'd never be able to fire the bullet straight up. The forces would be > equal. That's true. With the force of gravity, everything falls at the same speed, which is about 7 meter per second or something like that (hey, I can't remember everything!:) When the bullet looses momentum, it will begin to fall, and only accelerate to the speed gravity allows it, which is the same for everything, be it a bullet or a bus (give and take for air resistance). Now, at this speed, I'm sure someone could get -hurt- but a bullet, but seriously injured or killed is unlikely. -- Sandman[.net]
Edwin wrote: > > "Robert Bowmaker" <rob...@dse.gen.nz> wrote in > news:x7Vn8.1094$sO2...@news.xtra.co.nz: > > > Firing bullets straight up is a common occurence in many situations > > (i.e. warning shots, > > I would hope warning shots aren't a common occurance where you're from. ;-) I see you don't believe in the traditional warning before an Office tries to shoot someone. > > > shooting at the sky during a funeral for certain > > people etc.) > > Shooting done for a salute usually is done with blanks. > > > The question is: What actually happens to the bullet? Does it go into > > space? Does it fall back down? Does it burn up? None of the above? > > It falls back down. I don't know how much harm a few onces of lead will do > if it falls on you. ;-) > Depending on the speed of the few ounces of lead, it can kill you. -- Rick
On 26 Mar 2002 17:05:37 GMT, Edwin <zer...@aiur.org> wrote: >C Lund <chr...@NOSPAMchello.no> wrote in >news:chr...@news01.chello.no: > >> In article <x7Vn8.1094$sO2...@news.xtra.co.nz>, >> "Robert Bowmaker" <rob...@dse.gen.nz> wrote: >> >>> Firing bullets straight up is a common occurence in many situations >>> (i.e. warning shots, shooting at the sky during a funeral for certain >>> people etc.) >>> >>> The question is: What actually happens to the bullet? Does it go into >>> space? >> >> Unlikely. I don't think the bullet goes fast enough. >> >>> Does it fall back down? >> >> Yes. >> >>> Does it burn up? >> >> Unfortunatly, no. >> >> Not only does the bullet fall back down, but when it hits the ground, >> it's travelling at roughly the same speed as when it left the gun >> (minus a little for air resistance). I'm pretty sure people have been >> killed this way. > >No, the force of gravity acting on a few ounces of lead can't accelerate it >to the same velocity it had by being fired out of the gun. If it could, >you'd never be able to fire the bullet straight up. The forces would be >equal. > >Edwin But the unspoken question in this situation is 'Does the bullet have sufficient force on its way down to kill?' The answer to that is 'Yes'. Its stupid to fire a bullet into the air without a target in mind. If you just want to make some noise buy blanks. -- Road rage, air rage. Why should I be forced to divide my rage into seperate categories? To me, its just one big, all-around rage. I don't have time for fine distinctions. I'm busy screaming at people. George Carlin
In article<x7Vn8.1094$sO2...@news.xtra.co.nz>, Robert Bowmaker <rob...@dse.gen.nz> writes: >Firing bullets straight up is a common occurence in many situations (i.e. >warning shots, shooting at the sky during a funeral for certain people etc.) >The question is: What actually happens to the bullet? Does it go into space? >Does it fall back down? Does it burn up? None of the above? A bullet fired upward at an angle, especially a shallow angle, can lose its upward velocity quite soon (because gravity is decelerating it hard) while its horizontal velocity remains large (because air resistance is decelerating it quite gently), often large enough to kill or injure: people have been killed or injured in this way. You should avoid firing live rounds into the air in built up areas, as opposed to open country, because what goes up must come down somewhere. Planned firing for effect e.g. at funerals uses blank rounds Follow-ups considerably trimmed. In article<Pin...@esther.rad.tju.edu>, Dr. Michael Albert <alb...@esther.rad.tju.edu> writes: >They come back down, and they are quite capable of injuring people >and damaging property. > >In the city where I live, a few years back a child got a very >serious head injury (the bullet penetrated the skull) from >a bullet apparently fired into the air for a New Year's >celebration. (Sorry, I don't know the outcome). -- . . : : ,; . : ' ___. uno, dos, tres, |FUEGO| .:. .:. .:': :' .:':' :. . : (") #oH| ' ' :' : :' : .::. H_ ~~~| < > __ ,;;,. \\::// R_) | '-|"""(") {__}::===== ....'''' ' ' ' ___..\||/....L\. ...| ____||--|_'--/__\___ '' .--'''::::::::::::::::::::: \ / /////////////S.Coronado///// ;'^';-._.-;'^';-._.-;'^';-._.-;'^';-._;'^';-._.-;'^';-._.-;'^';-._.-;'^ LRon Hubbard is shelled by goats in hell <www.xemu.demon.co.uk/clam/ >
Edwin wrote: > C Lund <chr...@NOSPAMchello.no> wrote in > news:chr...@news01.chello.no: > > > In article <x7Vn8.1094$sO2...@news.xtra.co.nz>, > > "Robert Bowmaker" <rob...@dse.gen.nz> wrote: > > > >> Firing bullets straight up is a common occurence in many situations > >> (i.e. warning shots, shooting at the sky during a funeral for certain > >> people etc.) > >> > >> The question is: What actually happens to the bullet? Does it go into > >> space? > > > > Unlikely. I don't think the bullet goes fast enough. > > > >> Does it fall back down? > > > > Yes. > > > >> Does it burn up? > > > > Unfortunatly, no. > > > > Not only does the bullet fall back down, but when it hits the ground, > > it's travelling at roughly the same speed as when it left the gun > > (minus a little for air resistance). I'm pretty sure people have been > > killed this way. > > No, the force of gravity acting on a few ounces of lead can't accelerate it > to the same velocity it had by being fired out of the gun. If it could, > you'd never be able to fire the bullet straight up. The forces would be > equal. > Back to physics class for you. In the absence of air resistance the speed will be identical. Think: what force is slowing the bullet from its initial speed to rest? What force accelerates the bullet from rest as it descends? How long does it act for in each case? D.
| David Squire wrote: |> Edwin wrote: |>> C Lund wrote: |>>> Robert Bowmaker wrote: |>>> Firing bullets straight up is a common occurence in many situations |>>> (i.e. warning shots, shooting at the sky during a funeral for certain |>>> people etc.) |>>> The question is: What actually happens to the bullet? Does it go into |>>> space? |>> Unlikely. I don't think the bullet goes fast enough. |>>> Does it fall back down? |>> Yes. |>>> Does it burn up? |>> Unfortunatly, no. |>> Not only does the bullet fall back down, but when it hits the ground, |>> it's travelling at roughly the same speed as when it left the gun |>> (minus a little for air resistance). I'm pretty sure people have been |>> killed this way. |> No, the force of gravity acting on a few ounces of lead can't accelerate it |> to the same velocity it had by being fired out of the gun. If it could, |> you'd never be able to fire the bullet straight up. The forces would be |> equal. | Back to physics class for you. In the absence of air resistance the speed will | be identical. | | Think: what force is slowing the bullet from its initial speed to rest? What | force accelerates the bullet from rest as it descends? How long does it act | for in each case? Not A force, but two forces are acting on the bullet to slow it down: gravity, and air resistance. It should be noted that air resistance is larger when the bullet speed is higher. ----------------------------------- Gerard S.
> That's true. With the force of gravity, everything falls at the same speed, > which is about 7 meter per second or something like that (hey, I can't > remember everything!:) I think your thinking of the 9.8 meters per second per second (yes, there are TWO 'per second' clauses) ACCELERATION due to gravity. Everything gets the same acceleration, not the same speed. > When the bullet looses momentum, it will begin to fall, and only accelerate > to the speed gravity allows it, which is the same for everything, be it a > bullet or a bus (give and take for air resistance). I think air resistance is more than a little note to put in brackets - especially when you consider parachutes. Parachutes have a terminal velocity of about 0.5 to 1 m/s (don't quote me on that...), but a nicely shaped piece of lead probably goes at hundreds of m/s. Of course, in a (perfect) vacuum, terminal velocity is infinite - until it gets close to the speed of light! > Now, at this speed, I'm sure someone could get -hurt- but a bullet, but > seriously injured or killed is unlikely. OK, does anyone have a bus to drop on this guy? He seems to think that he'll be all right.
On Tue, 26 Mar 2002 21:06:38 GMT, Anil <aniltr@SELDOM_CHECKEDhotmail.com> wrote in message <yp5o8.83$s4....@news.uchicago.edu>: >Edwin <zer...@aiur.org> wrote: >>No, the force of gravity acting on a few ounces of lead can't >>accelerate it to the same velocity it had by being fired out of the gun. >Gravity accelerates everything equally, lead or iron, a few ounces or >many tons. Surprisingly perhaps (depends on what you know), without >air resistence, anything thrown vertically upwards will come down and >hit the ground with the same speed. The faster the initial speed. >The higher it goes before starting downwards and therefore the longer >the gravity has to accelerate it: it all works out. >In practice, air resistance will slow it down. unless the object achieves escape velocity... -- bes...@last.com V ybir lbh nyy. Lbh ner nyy fhpu fcrpvny crbcyr. Naq abj V unir gb xvyy lbh.
On 26 Mar 2002 17:05:37 GMT
Edwin <zer...@aiur.org> wrote:
E> No, the force of gravity acting on a few ounces of lead can't accelerate it
E> to the same velocity it had by being fired out of the gun. If it could,
E> you'd never be able to fire the bullet straight up. The forces would be
E> equal.
Wrong! You are confusing force and impulse.
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David Squire wrote: > > "Dr. Rev. Chuck, M.D., P.A." wrote: > > > David Squire wrote: > > > > > > "Dr. Rev. Chuck, M.D., P.A." wrote: > > > > > > > none wrote: > > > > > > > > > > As far as comparing them to rain... Lead is a lot heavier than water and > > > > > will come down quite a bit faster, > > > > > > > > Nope. > > > > > > If its in a pellet the same size and shape it will. The force due to air > > > resistance will be the same in both cases, whereas the force due to gravity > > > will be higher on the lead pellet, due to its higher mass - it is more than > > > 11 times more dense. > > > > Does the name "Galileo" ring a bell? > > Does "in a vacuum" ring a bell? > > Galileo's result is true only in the absence of air resistance. You can try it at > home: drop a feather and a ball bearing from the same height and time their > descents. > > D. If you ring a bell in a vacuum does it make a sound? Elizabeth
Elizabeth wrote: > David Squire wrote: >> >> "Dr. Rev. Chuck, M.D., P.A." wrote: >> >> > David Squire wrote: >> > > >> > > "Dr. Rev. Chuck, M.D., P.A." wrote: >> > > >> > > > none wrote: >> > > > > >> > > > > As far as comparing them to rain... Lead is a lot heavier than >> > > > > water and will come down quite a bit faster, >> > > > >> > > > Nope. >> > > >> > > If its in a pellet the same size and shape it will. The force due to >> > > air resistance will be the same in both cases, whereas the force due >> > > to gravity will be higher on the lead pellet, due to its higher mass >> > > - it is more than 11 times more dense. >> > >> > Does the name "Galileo" ring a bell? >> >> Does "in a vacuum" ring a bell? >> >> Galileo's result is true only in the absence of air resistance. You can >> try it at home: drop a feather and a ball bearing from the same height >> and time their descents. >> >> D. > If you ring a bell in a vacuum does it make a sound? > Elizabeth Sure it does. You just must be somehow attached to it to hear it. The absence of a transport medium is just that, no way to *transport* the sound, which is still there (at the bell) Peter -- Get the new Windows XP. Now with eXtra Problems included
"Elizabeth" <boo...@greyREMOVErock.org> wrote in message news:3CA...@greyREMOVErock.org... > David Squire wrote: > > > > "Dr. Rev. Chuck, M.D., P.A." wrote: > > > > > David Squire wrote: > > > > > > > > "Dr. Rev. Chuck, M.D., P.A." wrote: > > > > > > > > > none wrote: > > > > > > > > > > > > As far as comparing them to rain... Lead is a lot heavier than water and > > > > > > will come down quite a bit faster, > > > > > > > > > > Nope. > > > > > > > > If its in a pellet the same size and shape it will. The force due to air > > > > resistance will be the same in both cases, whereas the force due to gravity > > > > will be higher on the lead pellet, due to its higher mass - it is more than > > > > 11 times more dense. > > > > > > Does the name "Galileo" ring a bell? > > > > Does "in a vacuum" ring a bell? > > > > Galileo's result is true only in the absence of air resistance. You can try it at > > home: drop a feather and a ball bearing from the same height and time their > > descents. > > > > D. > If you ring a bell in a vacuum does it make a sound? You probably know the answer to that one Elizabeth, but i will try to enlighten all who don't know. Sound waves need some form of matter in order to travel. Since there is no form of matter in a perfect vacuum, one would have to conclude that the sound waves travel only through the object that made the sound, i.e. the bell. Am I close? > Elizabeth
On Wed, 27 Mar 2002 20:47:53 GMT, "Not Here" <not...@microsoft.com> wrote in message <Zdqo8.232379$s43...@typhoon.columbus.rr.com>: >"Elizabeth" <boo...@greyREMOVErock.org> wrote in message >news:3CA...@greyREMOVErock.org... >> David Squire wrote: >> > >> > "Dr. Rev. Chuck, M.D., P.A." wrote: >> > >> > > David Squire wrote: >> > > > >> > > > "Dr. Rev. Chuck, M.D., P.A." wrote: >> > > > >> > > > > none wrote: >> > > > > > >> > > > > > As far as comparing them to rain... Lead is a lot heavier than >water and >> > > > > > will come down quite a bit faster, >> > > > > >> > > > > Nope. >> > > > >> > > > If its in a pellet the same size and shape it will. The force due to >air >> > > > resistance will be the same in both cases, whereas the force due to >gravity >> > > > will be higher on the lead pellet, due to its higher mass - it is >more than >> > > > 11 times more dense. >> > > >> > > Does the name "Galileo" ring a bell? >> > >> > Does "in a vacuum" ring a bell? >> > >> > Galileo's result is true only in the absence of air resistance. You can >try it at >> > home: drop a feather and a ball bearing from the same height and time >their >> > descents. >> > >> > D. >> If you ring a bell in a vacuum does it make a sound? > >You probably know the answer to that one Elizabeth, but i will try to >enlighten all who don't know. Sound waves need some form of matter in order >to travel. Since there is no form of matter in a perfect vacuum, one would >have to conclude that the sound waves travel only through the object that >made the sound, i.e. the bell. Am I close? in space, no one can hear you scream... -- bes...@last.com V ybir lbh nyy. Lbh ner nyy fhpu fcrpvny crbcyr. Naq abj V unir gb xvyy lbh.
Peter K�hlmann <Pet...@t-online.de> espoused: >Elizabeth wrote: > >> David Squire wrote: >>> >>> "Dr. Rev. Chuck, M.D., P.A." wrote: >>> >>> > David Squire wrote: >>> > > >>> > > "Dr. Rev. Chuck, M.D., P.A." wrote: >>> > > >>> > > > none wrote: >>> > > > > >>> > > > > As far as comparing them to rain... Lead is a lot heavier than >>> > > > > water and will come down quite a bit faster, >>> > > > >>> > > > Nope. >>> > > >>> > > If its in a pellet the same size and shape it will. The force due to >>> > > air resistance will be the same in both cases, whereas the force due >>> > > to gravity will be higher on the lead pellet, due to its higher mass >>> > > - it is more than 11 times more dense. >>> > >>> > Does the name "Galileo" ring a bell? >>> >>> Does "in a vacuum" ring a bell? >>> >>> Galileo's result is true only in the absence of air resistance. You can >>> try it at home: drop a feather and a ball bearing from the same height >>> and time their descents. >>> >>> D. >> If you ring a bell in a vacuum does it make a sound? >> Elizabeth > >Sure it does. You just must be somehow attached to it to hear it. >The absence of a transport medium is just that, no way to *transport* the >sound, which is still there (at the bell) > Ahhh - that's an interesting logical conundrum. It's a question of how you define sound. If you say 'does a bell vibrate in a vacuum after being hit" then the answer is certainly yes. If you say 'does it make a sound'? then I think that depends on whether you have something else to transmit the vibrations. Define sound, then you have the range of answers available. -- | Mark Kent -- Take out the ham to mail me. | Revolution, n.: A form of government abroad.
Peter K�hlmann wrote: > > Elizabeth wrote: > > > David Squire wrote: > >> > >> "Dr. Rev. Chuck, M.D., P.A." wrote: > >> > >> > David Squire wrote: > >> > > > >> > > "Dr. Rev. Chuck, M.D., P.A." wrote: > >> > > > >> > > > none wrote: > >> > > > > > >> > > > > As far as comparing them to rain... Lead is a lot heavier than > >> > > > > water and will come down quite a bit faster, > >> > > > > >> > > > Nope. > >> > > > >> > > If its in a pellet the same size and shape it will. The force due to > >> > > air resistance will be the same in both cases, whereas the force due > >> > > to gravity will be higher on the lead pellet, due to its higher mass > >> > > - it is more than 11 times more dense. > >> > > >> > Does the name "Galileo" ring a bell? > >> > >> Does "in a vacuum" ring a bell? > >> > >> Galileo's result is true only in the absence of air resistance. You can > >> try it at home: drop a feather and a ball bearing from the same height > >> and time their descents. > >> > >> D. > > If you ring a bell in a vacuum does it make a sound? > > Elizabeth > > Sure it does. You just must be somehow attached to it to hear it. > The absence of a transport medium is just that, no way to *transport* the > sound, which is still there (at the bell) I remember that one on the old Johny Carson show... Johny: If there is no one in the forest and a tree falls, would there be a sound? Someone in the audience: Help! I've fallen and I can't get up! 5 minutes of uproarious laughter followed.
Elizabeth <boo...@greyREMOVErock.org> spake thus: news:3CA...@greyREMOVErock.org: > David Squire wrote: >> >> "Dr. Rev. Chuck, M.D., P.A." wrote: >> >> > David Squire wrote: >> > > >> > > "Dr. Rev. Chuck, M.D., P.A." wrote: >> > > >> > > > none wrote: >> > > > > >> > > > > As far as comparing them to rain... Lead is a lot heavier >> > > > > than water and will come down quite a bit faster, >> > > > >> > > > Nope. >> > > >> > > If its in a pellet the same size and shape it will. The force due >> > > to air resistance will be the same in both cases, whereas the >> > > force due to gravity will be higher on the lead pellet, due to >> > > its higher mass - it is more than 11 times more dense. >> > >> > Does the name "Galileo" ring a bell? >> >> Does "in a vacuum" ring a bell? >> >> Galileo's result is true only in the absence of air resistance. You >> can try it at home: drop a feather and a ball bearing from the same >> height and time their descents. >> >> D. > If you ring a bell in a vacuum does it make a sound? > Elizabeth Technically, yes. In practice, no. There is no air to transmit the sound. We hear it's vibrations (ring) but take away the air and it still vibrates. -- Rev Phylter ULC Ordained minister Denizen of Darkness #44 AFJC Antipodean Attach� http://www.rudraigh.com/afjc/regulars.html Pray. To ask the laws of the universe to be annulled on behalf of a single petitioner confessedly unworthy. Ambrose Bierce (1842-1914)
"Edwin" <zer...@aiur.org> wrote in message news:a7q9p0$n6or0$2...@ID-56786.news.dfncis.de... > C Lund <chr...@NOSPAMchello.no> wrote in > news:chr...@news01.chello.no: > > > In article <x7Vn8.1094$sO2...@news.xtra.co.nz>, > > "Robert Bowmaker" <rob...@dse.gen.nz> wrote: > > > >> Firing bullets straight up is a common occurence in many situations > >> (i.e. warning shots, shooting at the sky during a funeral for certain > >> people etc.) > >> > >> The question is: What actually happens to the bullet? Does it go into > >> space? > > > > Unlikely. I don't think the bullet goes fast enough. > > > >> Does it fall back down? > > > > Yes. > > > >> Does it burn up? > > > > Unfortunatly, no. > > > > Not only does the bullet fall back down, but when it hits the ground, > > it's travelling at roughly the same speed as when it left the gun > > (minus a little for air resistance). I'm pretty sure people have been > > killed this way. > > No, the force of gravity acting on a few ounces of lead can't accelerate it > to the same velocity it had by being fired out of the gun. If it could, > you'd never be able to fire the bullet straight up. The forces would be > equal. > If there were no atmosphere, then it would have exactly the same velocity when it came down than when it left the gun. Ric
Sandman <m...@sandman.net> wrote in message news:<mr-...@news.fu-berlin.de>... > In article <a7q9p0$n6or0$2...@ID-56786.news.dfncis.de>, Edwin <zer...@aiur.org> > wrote: > > > > Not only does the bullet fall back down, but when it hits the ground, > > > it's travelling at roughly the same speed as when it left the gun > > > (minus a little for air resistance). I'm pretty sure people have been > > > killed this way. > > > > No, the force of gravity acting on a few ounces of lead can't accelerate it > > to the same velocity it had by being fired out of the gun. If it could, > > you'd never be able to fire the bullet straight up. The forces would be > > equal. > > That's true. With the force of gravity, everything falls at the same speed, > which is about 7 meter per second or something like that (hey, I can't > remember everything!:) That would be 9.81 m/s2 << squared. > > When the bullet looses momentum, it will begin to fall, and only accelerate > to the speed gravity allows it, which is the same for everything, be it a > bullet or a bus (give and take for air resistance). > > Now, at this speed, I'm sure someone could get -hurt- but a bullet, but > seriously injured or killed is unlikely.
MJP <mik...@bluedwarf.spam.net> wrote:
[snip]
All well and good, but how about stopping all this flippin'
cross-posting to irrelevant newsgroups?
Rowland.
[FU set]
--
Remove the animal for email address: row...@dog.physics.org
PGP pub key 0x62DCCA78 Sorry - the spam got to me
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UK biker? Join MAG and help keep bureaucracy at bay
MJP <mik...@bluedwarf.spam.net> wrote:
[snip]
Yes, but do please stop this excessive cross-posting.
Rowland.
[FU set]
--
Remove the animal for email address: row...@dog.physics.org
PGP pub key 0x62DCCA78 Sorry - the spam got to me
http://www.mag-uk.org
UK biker? Join MAG and help keep bureaucracy at bay
Not Here wrote: > > "Elizabeth" <boo...@greyREMOVErock.org> wrote in message > news:3CA...@greyREMOVErock.org... > > David Squire wrote: > > > > > > "Dr. Rev. Chuck, M.D., P.A." wrote: > > > > > > > David Squire wrote: > > > > > > > > > > "Dr. Rev. Chuck, M.D., P.A." wrote: > > > > > > > > > > > none wrote: > > > > > > > > > > > > > > As far as comparing them to rain... Lead is a lot heavier than > water and > > > > > > > will come down quite a bit faster, > > > > > > > > > > > > Nope. > > > > > > > > > > If its in a pellet the same size and shape it will. The force due to > air > > > > > resistance will be the same in both cases, whereas the force due to > gravity > > > > > will be higher on the lead pellet, due to its higher mass - it is > more than > > > > > 11 times more dense. > > > > > > > > Does the name "Galileo" ring a bell? > > > > > > Does "in a vacuum" ring a bell? > > > > > > Galileo's result is true only in the absence of air resistance. You can > try it at > > > home: drop a feather and a ball bearing from the same height and time > their > > > descents. > > > > > > D. > > If you ring a bell in a vacuum does it make a sound? > > You probably know the answer to that one Elizabeth, but i will try to > enlighten all who don't know. Sound waves need some form of matter in order > to travel. Since there is no form of matter in a perfect vacuum, one would > have to conclude that the sound waves travel only through the object that > made the sound, i.e. the bell. Am I close? > It was sort of a joke question. I haven't studied physics for a while, but IIRC, it doesn't make a sound. I guess we're talking about a closed system, so the energy required to ring the bell must come from within, and barring no other forces involved, the bell would vibrate indefinitely. Now I wonder if there's a small amount of heat involved in the transfer of energy. Anybody know? I haven't thought about this stuff in ages! Elizabeth
Edwin <zer...@aiur.org> wrote in message news:<a7q95c$n6or0$1...@ID-56786.news.dfncis.de>... > "Robert Bowmaker" <rob...@dse.gen.nz> wrote in > news:x7Vn8.1094$sO2...@news.xtra.co.nz: > > > The question is: What actually happens to the bullet? Does it go into > > space? Does it fall back down? Does it burn up? None of the above? I got a bit interested in this problem so I tried to solve it, at first mathematically but thats a bit difficult. I came up to this differential equation V(t) = V(0) -g*t -cw*A*rho*t/2/M*(V(t))^2 which is to difficult to solve, so I wrote a programm to solve this problem. Here is it: ------ import java.io.*; public class Physik { // this Programm assumes constant gravity. START_VELOCITY should not // be to close to escape velocity public static final double START_VELOCITY=600.; //meters per second public static final double BULLET_MASS=.0059367; // kg public static final double BULLET_RADIUS=0.005; //m public static final double SPHERE_CW_VALUE=0.43; public static final double EARTH_ACCELERATION=9.81; // m/s^2 public static final double AIR_DENSITY=1.29; //kg*m^-3 public static void main(String[] args) { double velocity = START_VELOCITY; double altitude=0.1; long time=0; // milliseconds while(altitude>0) { time++; if(time%1000==0) { // Output every second System.out.println("Time: "+(int)(time/1000)+ " sec. Velocity: "+velocity+" Altitude:"+altitude+"m"); } if(velocity>0) { velocity -= (0.001*EARTH_ACCELERATION); // effects of gravity velocity -= 0.0005*SPHERE_CW_VALUE*Math.PI*BULLET_RADIUS* BULLET_RADIUS*AIR_DENSITY*velocity* velocity/BULLET_MASS;// effects of air resistance } else { velocity -= (0.001*EARTH_ACCELERATION); // effects of gravity velocity += 0.0005*SPHERE_CW_VALUE*Math.PI*BULLET_RADIUS* BULLET_RADIUS*AIR_DENSITY*velocity* velocity/BULLET_MASS;// effects of air resistance } altitude += 0.001*velocity; } System.out.println("End"); System.out.println("Time: "+time+" msec. Velocity: " +velocity+" Altitude:"+altitude+"m"); } } ------- And here is the output: Time: 1 sec. Velocity: 182.767329315557 Altitude:313.9889103484415m Time: 2 sec. Velocity: 102.93655324264626 Altitude:450.19204386384945m Time: 3 sec. Velocity: 67.28102752697508 Altitude:533.4695325824632m Time: 4 sec. Velocity: 45.885623795788625 Altitude:589.3113694914061m Time: 5 sec. Velocity: 30.721468003701805 Altitude:627.2551712330571m Time: 6 sec. Velocity: 18.66332461450972 Altitude:651.7606345423462m Time: 7 sec. Velocity: 8.168188312246363 Altitude:665.085517850534m Time: 8 sec. Velocity:-1.708012596526278 Altitude:668.2907108883071m Time: 9 sec. Velocity:-11.331565958315913 Altitude:661.7275295391529m Time: 10 sec. Velocity:-20.19517275872547 Altitude:645.8738977444464m Time: 11 sec. Velocity:-27.848887324834912 Altitude:621.7352040884126m Time: 12 sec. Velocity:-34.09827745002394 Altitude:590.6398258126908m Time: 13 sec. Velocity:-38.972018448610804 Altitude:553.9931841438874m Time: 14 sec. Velocity:-42.63856531226591 Altitude:513.0945060604246m Time: 15 sec. Velocity:-45.32292568279939 Altitude:469.040225796333m Time: 16 sec. Velocity:-47.24932123874531 Altitude:422.69864533895m Time: 17 sec. Velocity:-48.61203334409702 Altitude:374.7273849964622m Time: 18 sec. Velocity:-49.56622374124049 Altitude:325.60917279345995m Time: 19 sec. Velocity:-50.2296014059005 Altitude:275.6907170908416m Time: 20 sec. Velocity:-50.68850928763151 Altitude:225.2172953804121m Time: 21 sec. Velocity:-51.00487835669808 Altitude:174.36062359164038m Time: 22 sec. Velocity:-51.22246413502058 Altitude:123.2400549298544m Time: 23 sec. Velocity:-51.371866322071526 Altitude:71.93813718527623m Time: 24 sec. Velocity:-51.47433608682388 Altitude:20.511768627818906m End Time: 24398 msec. Velocity: -51.50557167546148 Altitude:-0.032895169707768394m As you should see its not really important how fast the bullet is shot, because air resistance evens the earth acceleration out. If the bullet falls a distance of about 490 meters(after it has reached the highest point) it gets a speed of about 50 m/s (180 km/h) which is probably enough to be very dangerous. This program simulates a direct vertical shot of a spherical lead bullet started with a 600 m/s (2160km/h). The bullet has a diameter of 5mm and weigths 5.9376g (I do not know if this is realistic). A bullet with a different size would probably reach an other velocity. If there's no wind, this bullet will reach its starting place 24 seconds after it was shot.(if there is wind, it will reach an other place in the same time with the same horizontal speed) I hop I brought some clarity into this discussion. If you want to test this program you need an installed Java SDK Paste the programm into an editor save as 'Physik.java' compile: 'javac Physik.java' run: 'java Physik'
Dr Scab wrote: > On 28 Mar 2002 12:14:52 -0800, in alt.ascii-art, > (dok...@gmx.de (Jonas M�ller)) wrote: > > >>Edwin <zer...@aiur.org> wrote in message news:<a7q95c$n6or0$1...@ID-56786.news.dfncis.de>... >> >>>"Robert Bowmaker" <rob...@dse.gen.nz> wrote in >>>news:x7Vn8.1094$sO2...@news.xtra.co.nz: >>> >>> >>>>The question is: What actually happens to the bullet? Does it go into >>>>space? Does it fall back down? Does it burn up? None of the above? >>>> >>I got a bit interested in this problem so I tried to solve it, at >>first mathematically but thats a bit difficult. >>I came up to this differential equation >> >>V(t) = V(0) -g*t -cw*A*rho*t/2/M*(V(t))^2 >> >>which is to difficult to solve, so I wrote a programm to solve this >>problem. >>Here is it: >> >>------ >>import java.io.*; >>public class Physik { >> >>// this Programm assumes constant gravity. START_VELOCITY should not >>// be to close to escape velocity >> > > The gravity won't be constant. As the bullet moves away, the > gravity will decrease. > not significantly > > >
In article <a7q9p0$n6or0$2...@ID-56786.news.dfncis.de>, Edwin <zer...@aiur.org> wrote: > C Lund <chr...@NOSPAMchello.no> wrote in > news:chr...@news01.chello.no: > > > In article <x7Vn8.1094$sO2...@news.xtra.co.nz>, > > "Robert Bowmaker" <rob...@dse.gen.nz> wrote: > > > >> Firing bullets straight up is a common occurence in many situations > >> (i.e. warning shots, shooting at the sky during a funeral for certain > >> people etc.) > >> > >> The question is: What actually happens to the bullet? Does it go into > >> space? > > > > Unlikely. I don't think the bullet goes fast enough. > > > >> Does it fall back down? > > > > Yes. > > > >> Does it burn up? > > > > Unfortunatly, no. > > > > Not only does the bullet fall back down, but when it hits the ground, > > it's travelling at roughly the same speed as when it left the gun > > (minus a little for air resistance). I'm pretty sure people have been > > killed this way. > > No, This is right. > the force of gravity acting on a few ounces of lead can't accelerate it > to the same velocity it had by being fired out of the gun. If it could, > you'd never be able to fire the bullet straight up. The forces would be > equal. This is entirely wrong. You're right that the bullet wouldn't be moving nearly as fast. But it's air resistance that's responsible for the slower speed. Gravity simply applies a constant acceleration. Assuming you're in a vacuum, there's no limit (short of c) to the velocity it can impart. Why does the bullet leave the gun in the first place? Because gravity can't apply acceleration nearly as fast as the gun can. For the tens of seconds that it takes gravity to cancel the bullet's initial velocity, the bullet continues to move upward. If you fire a bullet straight up, it will climb to a certain hight. That hight is the hight at witch the force of gravity, over time, has applied enough acceleration to the bullet to exactly cancel out its upward momentum. It continues to apply just as much acceleration once the bullet has lost its initial speed. So the bullet will come down at exactly the same speed it was fired at. Unless something interferes, like a lot of air. -- We still feel that color is hard on the eyes for so long a picture. -- Frank S. Nugent of The New York Times in his 1939 review of Gone With the Wind
Jonas M�ller wrote: > Edwin <zer...@aiur.org> wrote in message news:<a7q95c$n6or0$1...@ID-56786.news.dfncis.de>... > >>"Robert Bowmaker" <rob...@dse.gen.nz> wrote in >>news:x7Vn8.1094$sO2...@news.xtra.co.nz: >> >> > >>>The question is: What actually happens to the bullet? Does it go into >>>space? Does it fall back down? Does it burn up? None of the above? >>> > > I got a bit interested in this problem so I tried to solve it, at > first mathematically but thats a bit difficult. > I came up to this differential equation > > V(t) = V(0) -g*t -cw*A*rho*t/2/M*(V(t))^2 > I set up an equation for free fall, where it is assumed by Stokes equation that the drag force is directly proportional to velocity. So I got the following: Fnet = mg - Dv where D is a drag coefficient ma = mg - Dv a = g - Dv/m d^2x/dt^2 = g - (D/m)*dx/dt using d^2x/dt^2 = gexp(-bt); because a(0) = g one gets that, dx/dt = mg/D(1-exp(-bt)); because a(infinity) = 0, so v(infinity) = mg/D= terminal velocity = (vT) using dv/dt = a one finds that b = D/mg = 1/(vT) so from integration of v(t) x(t) = (vT)t + (vT)*exp(-t/vT) + x(0)
Jonas M�ller wrote: > Edwin <zer...@aiur.org> wrote in message news:<a7q95c$n6or0$1...@ID-56786.news.dfncis.de>... > >>"Robert Bowmaker" <rob...@dse.gen.nz> wrote in >>news:x7Vn8.1094$sO2...@news.xtra.co.nz: >> >> > >>>The question is: What actually happens to the bullet? Does it go into >>>space? Does it fall back down? Does it burn up? None of the above? >>> > > I got a bit interested in this problem so I tried to solve it, at > first mathematically but thats a bit difficult. > I came up to this differential equation > > V(t) = V(0) -g*t -cw*A*rho*t/2/M*(V(t))^2 > This is the correct equation for one way only, but you handled it appropriately in your program with a while statement. > which is to difficult to solve, so I wrote a programm to solve this > problem. > Here is it: > > ------ > import java.io.*; > public class Physik { > > // this Programm assumes constant gravity. START_VELOCITY should not > // be to close to escape velocity > public static final double START_VELOCITY=600.; //meters per > second > public static final double BULLET_MASS=.0059367; // kg > public static final double BULLET_RADIUS=0.005; //m > public static final double SPHERE_CW_VALUE=0.43; > public static final double EARTH_ACCELERATION=9.81; // m/s^2 > public static final double AIR_DENSITY=1.29; //kg*m^-3 > > public static void main(String[] args) { > double velocity = START_VELOCITY; > double altitude=0.1; > long time=0; // milliseconds > > while(altitude>0) { > time++; > if(time%1000==0) { // Output every second > System.out.println("Time: "+(int)(time/1000)+ > " sec. Velocity: "+velocity+" Altitude:"+altitude+"m"); > } > if(velocity>0) { > velocity -= (0.001*EARTH_ACCELERATION); // effects of gravity > velocity -= 0.0005*SPHERE_CW_VALUE*Math.PI*BULLET_RADIUS* > BULLET_RADIUS*AIR_DENSITY*velocity* > velocity/BULLET_MASS;// effects of air resistance > } > else { > velocity -= (0.001*EARTH_ACCELERATION); // effects of gravity > velocity += 0.0005*SPHERE_CW_VALUE*Math.PI*BULLET_RADIUS* > BULLET_RADIUS*AIR_DENSITY*velocity* > velocity/BULLET_MASS;// effects of air resistance > } > altitude += 0.001*velocity; > } > System.out.println("End"); > System.out.println("Time: "+time+" msec. Velocity: " > +velocity+" Altitude:"+altitude+"m"); > } > } > ------- > And here is the output: > Time: 1 sec. Velocity: 182.767329315557 Altitude:313.9889103484415m > Time: 2 sec. Velocity: 102.93655324264626 > Altitude:450.19204386384945m > Time: 3 sec. Velocity: 67.28102752697508 Altitude:533.4695325824632m > Time: 4 sec. Velocity: 45.885623795788625 Altitude:589.3113694914061m > Time: 5 sec. Velocity: 30.721468003701805 Altitude:627.2551712330571m > Time: 6 sec. Velocity: 18.66332461450972 Altitude:651.7606345423462m > Time: 7 sec. Velocity: 8.168188312246363 Altitude:665.085517850534m > Time: 8 sec. Velocity:-1.708012596526278 Altitude:668.2907108883071m > Time: 9 sec. Velocity:-11.331565958315913 Altitude:661.7275295391529m > Time: 10 sec. Velocity:-20.19517275872547 Altitude:645.8738977444464m > Time: 11 sec. Velocity:-27.848887324834912 Altitude:621.7352040884126m > Time: 12 sec. Velocity:-34.09827745002394 Altitude:590.6398258126908m > Time: 13 sec. Velocity:-38.972018448610804 Altitude:553.9931841438874m > Time: 14 sec. Velocity:-42.63856531226591 Altitude:513.0945060604246m > Time: 15 sec. Velocity:-45.32292568279939 Altitude:469.040225796333m > Time: 16 sec. Velocity:-47.24932123874531 Altitude:422.69864533895m > Time: 17 sec. Velocity:-48.61203334409702 Altitude:374.7273849964622m > Time: 18 sec. Velocity:-49.56622374124049 Altitude:325.60917279345995m > Time: 19 sec. Velocity:-50.2296014059005 Altitude:275.6907170908416m > Time: 20 sec. Velocity:-50.68850928763151 Altitude:225.2172953804121m > Time: 21 sec. Velocity:-51.00487835669808 Altitude:174.36062359164038m > Time: 22 sec. Velocity:-51.22246413502058 Altitude:123.2400549298544m > Time: 23 sec. Velocity:-51.371866322071526 Altitude:71.93813718527623m > Time: 24 sec. Velocity:-51.47433608682388 Altitude:20.511768627818906m > End > Time: 24398 msec. Velocity: -51.50557167546148 > Altitude:-0.032895169707768394m > > As you should see its not really important how fast the bullet is > shot, because air resistance evens the earth acceleration out. If the > bullet falls a distance of about 490 meters(after it has reached the > highest point) it gets a speed of about 50 m/s (180 km/h) which is > probably enough to be very dangerous. > > This program simulates a direct vertical shot of a spherical lead > bullet started with a 600 m/s (2160km/h). The bullet has a diameter of > 5mm and weigths 5.9376g (I do not know if this is realistic). A bullet > with a different size would probably reach an other velocity. If > there's no wind, this bullet will reach its starting place 24 seconds > after it was shot.(if there is wind, it will reach an other place in > the same time with the same horizontal speed) > > > I hop I brought some clarity into this discussion. > > > If you want to test this program you need an installed Java SDK > > Paste the programm into an editor > save as 'Physik.java' > compile: 'javac Physik.java' > run: 'java Physik' >
In article <3CA...@greyREMOVErock.org>, Elizabeth <boo...@greyREMOVErock.org> wrote: > It was sort of a joke question. I haven't studied physics for a while, > but IIRC, it doesn't make a sound. I guess we're talking about a closed > system, so the energy required to ring the bell must come from within, > and barring no other forces involved, the bell would vibrate > indefinitely. Now I wonder if there's a small amount of heat involved in > the transfer of energy. Anybody know? I haven't thought about this stuff > in ages! The bell rings because someone hit it with something. Its ringing sets up pressure waves in the air, and we can hear those. In a vacuum, a bell might vibrate for longer than in an atmosphere because there's no atmosphere to carry energy away from it. However, internal friction of the moving metal will eventually damp the vibrations (and heat up the bell). Imagine this scenario: Rigidly attach a bell to the inside of a steel container. Evacuate the air from the container. Then ring the bell. (Okay, you can have an electromagnet with a hammer in there.) Assuming that you and the container are in an atmosphere, and the container isn't unreasonably thick, you might be able to hear the bell ringing even though it's in a vacuum. -- Timberwoof <timberwoof at infernosoft dot com> http://www.infernosoft.com/timberwoof/motorcycle/index.html a motorcycle faq: http://www.infernosoft.com/timberwoof/motorcycle/faq.shtml
"Timberwoof" wrote ... > Elizabeth <boo...@greyREMOVErock.org> wrote: > > > It was sort of a joke question. I haven't studied physics for a while, > > but IIRC, it doesn't make a sound. I guess we're talking about a closed > > system, so the energy required to ring the bell must come from within, > > and barring no other forces involved, the bell would vibrate > > indefinitely. Now I wonder if there's a small amount of heat involved in > > the transfer of energy. Anybody know? I haven't thought about this stuff > > in ages! > > The bell rings because someone hit it with something. Its ringing sets > up pressure waves in the air, and we can hear those. > > In a vacuum, a bell might vibrate for longer than in an atmosphere > because there's no atmosphere to carry energy away from it. However, > internal friction of the moving metal will eventually damp the > vibrations (and heat up the bell). > > Imagine this scenario: Rigidly attach a bell to the inside of a steel > container. Evacuate the air from the container. Then ring the bell. > (Okay, you can have an electromagnet with a hammer in there.) Assuming > that you and the container are in an atmosphere, and the container isn't > unreasonably thick, you might be able to hear the bell ringing even > though it's in a vacuum. Nope. You'll hear the steel container resonating to the vibrations of the bell. (You /did/ say it was a rigid attachment?) -- arjay Denizen of Darkness #111 Damned by Dore #42 Ubi dubium ibi libertas. > -- > Timberwoof <timberwoof at infernosoft dot com> > http://www.infernosoft.com/timberwoof/motorcycle/index.html > a motorcycle faq: http://www.infernosoft.com/timberwoof/motorcycle/faq.shtml
mer...@cars3.uchicago.edu wrote in message news:<zz2o8.65$s4....@news.uchicago.edu>... > In article <a7q9p0$n6or0$2...@ID-56786.news.dfncis.de>, Edwin <zer...@aiur.org> writes: > >C Lund <chr...@NOSPAMchello.no> wrote in > >news:chr...@news01.chello.no: > > > >> In article <x7Vn8.1094$sO2...@news.xtra.co.nz>, > >> "Robert Bowmaker" <rob...@dse.gen.nz> wrote: > >> > >>> Firing bullets straight up is a common occurence in many situations > >>> (i.e. warning shots, shooting at the sky during a funeral for certain > >>> people etc.) > >>> > >>> The question is: What actually happens to the bullet? Does it go into > >>> space? > >> > >> Unlikely. I don't think the bullet goes fast enough. > >> > >>> Does it fall back down? You are all forgetting that g is not a constant except near the Earth's surface and not even then!! Dennis the Menace > >> > >> Yes. > >> > >>> Does it burn up? > >> > >> Unfortunatly, no. > >> > >> Not only does the bullet fall back down, but when it hits the ground, > >> it's travelling at roughly the same speed as when it left the gun > >> (minus a little for air resistance). I'm pretty sure people have been > >> killed this way. > > > >No, the force of gravity acting on a few ounces of lead can't accelerate it > >to the same velocity it had by being fired out of the gun. If it could, > >you'd never be able to fire the bullet straight up. The forces would be > >equal. > > > Nope, that's wrong reasoning. The force of gravity is weaker but it > acts over far larger distance than the force propelling the bullet out > of the barrel. In the absence of air resistance, the bullet would > hit the ground at the same velocity at which it was fired up. Air > resistance changes this significantly, of course. > > Mati Meron | "When you argue with a fool, > mer...@cars.uchicago.edu | chances are he is doing just the same"
Chris Wiegand <wie...@alum.rpi.edunospamm> wrote: > jea...@ipricot.com wrote: > > > Le Fri, 29 Mar 2002 04:17:49 GMT > > Chris Wiegand <wie...@alum.rpi.edunospamm> dit: > > > >> From your posts it seems as if you believe that no energy is required > >>to move air particles. The work done by the air on the object will be > >>equal to the area under the drag-force vs. displacement curve. > >> > >> > > > > How much energy do you think I should require to move you out of > > comp.unix.bsd.* and stop all thoses cross-postings ? [snip] > just ignore the thread, how hard is that. You're quite right. As Emily Postnews tells us in <http://www.landfield.com/faqs/usenet/emily-postnews/part1/>: Q: How can I choose what groups to post in? A: Pick as many as you can, so that you get the widest audience. After all, the net exists to give you an audience. Ignore those who suggest you should only use groups where you think the article is highly appropriate. Pick all groups where anybody might even be slightly interested. Always make sure followups go to all the groups. In the rare event that you post a followup which contains something original, make sure you expand the list of groups. Never include a "Followup-to:" line in the header, since some people might miss part of the valuable discussion in the fringe groups. Rowland. P.S. Or you might try: <http://www.landfield.com/faqs/usenet/posting-rules/part1/> Be considerate with your use of network resources. Your individual usage may not seem like much compared to the net as a whole, but in aggregate, small savings in disk or CPU add up to a great deal. For instance, messages offering thanks, jibes, or congratulations will only need to be seen by the interested parties -- send these by mail rather than posting them. The same goes for simple questions, and especially for any form of "me too" posting. -- Remove the animal for email address: row...@dog.physics.org PGP pub key 0x62DCCA78 Sorry - the spam got to me http://www.mag-uk.org UK biker? Join MAG and help keep bureaucracy at bay
Bill Vermillion <b...@wjv.comREMOVE> wrote: [snip] > So you are discounting all the hot air in Washington DC in the > vicinity of the Congressional Office Building? Possibly, possibly; but do please stop cross-posting this thread to irrelevant newsgroups. Rowland. -- Remove the animal for email address: row...@dog.physics.org PGP pub key 0x62DCCA78 Sorry - the spam got to me http://www.mag-uk.org UK biker? Join MAG and help keep bureaucracy at bay
yowie <yow...@onthewaybacktothe.pub> wrote: > In article <3CA...@Jhuapl.edu>, Jam...@Jhuapl.edu says... > > > > the energy requiered to MOVE the air is called resistance, try > > > tstanding outside on a windy day. ry it again in a hurricane or > > > ttornado. then tell us there is no such thing as air resistance. > > > No energy is *required* to move *air*, doofis. > > Unlike "sciences" Big Fart, it just MOVES, > > Thank you Mr Aristotle, now explain how airplanes fly. [snip] This is, I think, only relevant to the physics newsgroups - could you stop cross-posting to the rest of 'em? Rowland. -- Remove the animal for email address: row...@dog.physics.org PGP pub key 0x62DCCA78 Sorry - the spam got to me http://www.mag-uk.org UK biker? Join MAG and help keep bureaucracy at bay
Rowland McDonnell wrote: > Chris Wiegand <wie...@alum.rpi.edunospamm> wrote: > > >> jea...@ipricot.com wrote: >> >> >>> Le Fri, 29 Mar 2002 04:17:49 GMT Chris Wiegand >>> <wie...@alum.rpi.edunospamm> dit: >>> >>> >>>> From your posts it seems as if you believe that no energy is >>>> required to move air particles. The work done by the air on >>>> the object will be equal to the area under the drag-force vs. >>>> displacement curve. >>>> >>>> >>> >>> How much energy do you think I should require to move you out of >>> comp.unix.bsd.* and stop all thoses cross-postings ? >> > > [snip] > > >> just ignore the thread, how hard is that. > > > You're quite right. As Emily Postnews tells us in > <http://www.landfield.com/faqs/usenet/emily-postnews/part1/>: > > Q: How can I choose what groups to post in? > > A: Pick as many as you can, so that you get the widest audience. After > all, the net exists to give you an audience. Ignore those who suggest > you should only use groups where you think the article is highly > appropriate. Pick all groups where anybody might even be slightly > interested. > > Always make sure followups go to all the groups. In the rare event that > you post a followup which contains something original, make sure you > expand the list of groups. Never include a "Followup-to:" line in the > header, since some people might miss part of the valuable discussion > in the fringe groups. > > Rowland. > > P.S. Or you might try: > > <http://www.landfield.com/faqs/usenet/posting-rules/part1/> > > Be considerate with your use of network resources. Your individual usage > may not seem like much compared to the net as a whole, but in aggregate, > small savings in disk or CPU add up to a great deal. For instance, > messages offering thanks, jibes, or congratulations will only need > to be seen by the interested parties -- send these by mail rather > than posting them. The same goes for simple questions, and especially > for any form of "me too" posting. Gotta love the Net Cop. He probably makes more Usenet traffic complaining about "off topic" posts than those posts generate themselves. ;-) Edwin -- "I use MacOS X (and ported *nix apps), MacOS 9, YDL linux, and window$ (though not voluntarily). Why do you call e a Linux user?" -- Rick Hatton, March 29, 2002
Edwin <zer...@aiur.org> wrote in message news:a7q9p0$n6or0$2...@ID-56786.news.dfncis.de... > C Lund <chr...@NOSPAMchello.no> wrote in > news:chr...@news01.chello.no: > > > In article <x7Vn8.1094$sO2...@news.xtra.co.nz>, > > "Robert Bowmaker" <rob...@dse.gen.nz> wrote: > > > >> Firing bullets straight up is a common occurence in many situations > >> (i.e. warning shots, shooting at the sky during a funeral for certain > >> people etc.) > >> > >> The question is: What actually happens to the bullet? Does it go into > >> space? > > > > Unlikely. I don't think the bullet goes fast enough. > > > >> Does it fall back down? > > > > Yes. > > > >> Does it burn up? > > > > Unfortunatly, no. > > > > Not only does the bullet fall back down, but when it hits the ground, > > it's travelling at roughly the same speed as when it left the gun > > (minus a little for air resistance). I'm pretty sure people have been > > killed this way. > > No, the force of gravity acting on a few ounces of lead can't accelerate it > to the same velocity it had by being fired out of the gun. If it could, > you'd never be able to fire the bullet straight up. The forces would be > equal. Edwin needs to look again at the problem, and bring to bear some thoughts about conservation of energy. Franz Heymann
Edwin <zer...@aiur.org> wrote:
[snip]
> Oops! Forgot about that. I stand corrected. :-)
Well, you do now: do please stop cross-posting this to the irrelevant
newsgroups.
Thanks,
Rowland.
--
Remove the animal for email address: row...@dog.physics.org
PGP pub key 0x62DCCA78 Sorry - the spam got to me
http://www.mag-uk.org
UK biker? Join MAG and help keep bureaucracy at bay
James Hunter <Jam...@Jhuapl.edu> wrote: [snip] > My posts do imply that. My posts usually are meant > to *imply*, to *insinuate*, to *reinforce the believe* that > people who believe that energy *exists* are > clutching-at-straws, grasping-at-the-null-set MORONS. Okay, but could you please stop cross-posting to the irrelevant newsgroups? Rowland. -- Remove the animal for email address: row...@dog.physics.org PGP pub key 0x62DCCA78 Sorry - the spam got to me http://www.mag-uk.org UK biker? Join MAG and help keep bureaucracy at bay
In article <UpOo8.9545$n82...@news20.bellglobal.com>, "arjay" <arj...@sympatico.ca> wrote: > "Timberwoof" wrote ... > > Elizabeth <boo...@greyREMOVErock.org> wrote: > > > > > It was sort of a joke question. I haven't studied physics for a while, > > > but IIRC, it doesn't make a sound. I guess we're talking about a closed > > > system, so the energy required to ring the bell must come from within, > > > and barring no other forces involved, the bell would vibrate > > > indefinitely. Now I wonder if there's a small amount of heat involved in > > > the transfer of energy. Anybody know? I haven't thought about this stuff > > > in ages! > > > > The bell rings because someone hit it with something. Its ringing sets > > up pressure waves in the air, and we can hear those. > > > > In a vacuum, a bell might vibrate for longer than in an atmosphere > > because there's no atmosphere to carry energy away from it. However, > > internal friction of the moving metal will eventually damp the > > vibrations (and heat up the bell). > > > > Imagine this scenario: Rigidly attach a bell to the inside of a steel > > container. Evacuate the air from the container. Then ring the bell. > > (Okay, you can have an electromagnet with a hammer in there.) Assuming > > that you and the container are in an atmosphere, and the container isn't > > unreasonably thick, you might be able to hear the bell ringing even > > though it's in a vacuum. > > Nope. > You'll hear the steel container resonating to the vibrations of the bell. > (You /did/ say it was a rigid attachment?) What do you mean, "Nope"? That's what I said. -- Timberwoof <timberwoof at infernosoft dot com> Chief Perpetrator Infernosoft: Putting the No in Innovation. http://www.infernosoft.com "The opposite of hardware is not easyware."
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