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Random questions

  1. Mar 17, 2005 #1
    Could you fire a gun in an evironment where the pressure exerted on the bullet from the powder exploding was equal to atmosphere.

    Why wouldnt a self contained cartridge work in space, considering there is O2 in the cartridge.

    when you rub two things together, how is this sound formed? i dont understand the charecteristics/reasons behind sound

    if there was a perfect hole drilled through the earth, and it was hollow, would you be crushed in the middle, or would you just yoyo back and forth until you hovered in the center after all your force was cancelled out.

    more to come
     
  2. jcsd
  3. Mar 17, 2005 #2
    Haha, that would certainly be the upper limit (although the gun would probably fail at significantly lower pressures).

    Sound is a wave in the air (like waves in water). When you cause a disturbance in the air (water) the disturbance spreads out as a wave. Humans have evolved to "hear" these disturbances, and distinguish between them based on differing wave forms.

    Also, when two things collide, kinetic energy is often lost. This must become other types of energy such as heat, and acoustic waves (sound).

    This is correct. (Force doesn't cancelthough, its the wind resistance slowly draining your energy)
     
  4. Mar 17, 2005 #3

    Danger

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    Hi there;
    Maybe I misunderstood the question about the gun. If you meant that the detonating propellant produces one atmosphere of pressure, then nothing would happen. A cartridge is sealed at the ambient atmospheric pressure where it is made. If you meant that you're firing the gun in an environment where the atmospheric pressure is upwards of 20,000 psi, I doubt that you'd be in any condition to care what happens.
     
  5. Mar 17, 2005 #4

    vcc

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    I wonder what ignition looks like without any pressure release. Now that would be interesting.
     
  6. Mar 17, 2005 #5

    Alkatran

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    It probably looks like the gun crumpling up into a tiny little ball along with everything else at that pressure.
     
  7. Mar 17, 2005 #6

    vcc

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    hmm but that would happen prior to ignition :rofl:
     
  8. Mar 18, 2005 #7

    Danger

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    The gun itself probablly wouldn't notice any adverse effect. After all, it's built to contain that pressure in the first place. The cartridge would collapse, because it would effectively be a vacuum inside.
     
  9. Mar 18, 2005 #8

    Danger

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    Forgot to mention, the main reason that the gun would be okay is because it's an open structure that doesn't contain any air space to collapse. (Unless perhaps a 'scope, laser sight, or hollow plastic stocks.)
     
  10. Mar 18, 2005 #9
    so sound waves are actully energy, kinetic at that?

    Ok, the gun question. IF the gun's cartridge was the latest titanium alloy that would not crumple under pressure, and say the gun fired at 100psi-yet the atmosphere was also 100psi what would happen? the reason for igniting the gunpowder is to create higher pressure, higher pressure seaks to equalize. so if it was already equalized, my guess is that the chemical reaction would not happen-which has to be a violation of some law.

    same instance, if you tried to fire the gun but now maybe you are firing at 110psi in 100psi environment, the gun would have a very low decibal rating, correct?

    why arent planets perfect spheres

    there is this place out in the western usa where there are strange physics anomolies, i forget what its called but i would like to look into it. im sure someone on here has heard of it
     
  11. Mar 18, 2005 #10
    Yes, basically. It's movement, if that's what you mean.

    What do you mean the gun 'fires at 100psi'? Where is this pressure on/in the gun?

    Because of gravity. The center of the planet is the center of gravity, and a sphere is where the molecules can get the closest.

    Maybe you are talking about Area 51, basically an area where the united states allegedly keeps and tests rebuilt and captured alien spacecraft?
     
  12. Mar 18, 2005 #11

    purely theoretical, the pressure from the exploding cartridge is 100psi.

    yes because of gravity, the planet should be perfectly spherical, but it is ovular.

    no not area 51. its in a northwestern state. its like at a cabin or something, gravity is different, things appear different, just strange in general. and indians knew about it for a long time and worshipped it i think.
     
  13. Mar 18, 2005 #12
    What are you referring to with the planets? I believe what you are saying is "why are planets oblate spheroids?", and its basically because of the inertia of the planet spinning about its axis, which makes the mass on the 'sides' tend to 'fling off' more. Of course, they dont fling off, but overall that mass stretches a bit. I have been trying not to say centrifugal force, but I will just for simplicity's sake. Yes, I know it's not a real force but the result of other principles.

    As far as the cabin, never heard of it. You'll have to think of it or find it. Either way it sounds like a load of BS. (not on your part, I mean its probably an urban legend)
     
  14. Mar 20, 2005 #13

    Danger

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    The point I was getting at is that the cartridge is essentially a vacuum chamber containing the chemicals. When it is fired, the expansion brings it up to atmospheric equilibrium. Therefore, no movement of bullet, just no more stress on hull.
     
  15. Mar 20, 2005 #14

    Danger

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    The only sound that would be made would be mechanical noises of the gun itself, and you cursing at the fleeing back of your prey. 110psi isn't enough to dislodge a bullet from the cartridge case. It might puff up a bit within the size tolerance of the chamber, since brass is pretty soft, but it wouldn't fire.
     
  16. Mar 20, 2005 #15

    Danger

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    Whoa! Just reread that quote. Missed the part about 100psi environment. That would make your net pressure gain within the cartridge 10psi. Carrying the cartridge up a small mountain or on a plane would raise the differential higher than that. Nothing at all would happen, except perhaps it would heat up from the combustion.
     
  17. Mar 20, 2005 #16

    Danger

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    I haven't heard of that one, but it might be similar to Magnetic Hill in our maritimes (Nova Scotia?). That's where a stream runs uphill, and if you leave your car in neutral it'll take off down the road on it's own. The whole thing is neat, but just an optical illusion. Peculiarities of the landscape would make you swear that you're standing on level ground, when it's actually a slope.
     
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