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Bullet string

  1. Jan 7, 2005 #1
    ok, heres my problem, lets say you had a bullet and ignoring the physics of teh gun being shot(by this i meen the gunpowder explosion), what would happen if a string were tied to teh back of that bullet? would it slow it down considerably? would it effect where teh bullet goes?

    Just wondering

  2. jcsd
  3. Jan 8, 2005 #2


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    Well you'd have to tie it real fast, as that bullet is moving real fast. Probably the string would break.
    Nah, the string would probably speed up until it broke.

    Are you planning to become a whale hunter (harpoon and rope)?
  4. Jan 14, 2005 #3

    lololol no i cant say it was the plan, now that i tjhikn of it im not completely sure why i wanted to know this lol, anyway, waht i meant was if the string was already tied before the bullet was shot so i wouldnt have to tie it on as it was shot, it would be already on as it was fired. also, just for the sake of siscussion, lets say it was some very strong string, not necacerially string so much as...uhm, well lets just say very strong string lol. anyway my question would be, if that string got cought up in teh spokes, and saying the string didnt break, being the unbreakable miracle string it is, would th bullet stop? would the gun be pulled forward incredibly fast? also, after a while, the string would have to be adding extra weight to that bullet so it probably couldnt go as far, right?


    now that i look at this it seems a smidge rediculous loolol
  5. Jan 16, 2005 #4


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    The harpoon is a much better example. Harpoons are fired out of a cannon, an have a rope attached. The mass of the rope affects the speed and trajectory of the harpoon. Would be more insteresting if this wasn't used to kill whales.
  6. Jan 16, 2005 #5


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    In the navy, the first line sent across between two ships when you need to transfer cargo between them is a "shot line." I'm not entirely sure how it works, but its a spool of string attached to a regular rifle. It flies maybe 200yd, on a high trajectory.
  7. Jan 16, 2005 #6
    What if the string had negligible mass, but would be strong enough not to break and the bullet had mass, but would not get untied from the rope. The string is also tied to something. As the bullet travels it will draw the string behind it. When the bullet has traveled the length of the string, will it decelerate instantaneously?
  8. Jan 16, 2005 #7


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    No the string will stretch. Everything reacts to a force with some amount of compression or expansion near the point of application (ignoring cases like free-fall under gravititational force). A stress versus strain graph for that material indicates by how much.
  9. Jan 17, 2005 #8
    but the thing is, as the length of the string increses, the mass of the bullet+string increses and therefore wiould decrese how far it could go right? or might the wake of the bullet keep the string aloft without a whole lot fo friction, im not sure if wake was trhe best word, what i meen is, the area directly behind the bullet where the air has been pushed out of the way. would that keep the string from sinking? either wayit would add mre mass to the bullet and that would still slow it down...i thnk this kind of thing might be used as like a really advanced grapling hook, like if you wanted to hook up to a plane directly above you, you could fire this and then hope you can pull yourself up before its too late lol, so technically it wount be a bullet so muchas a very small grappler, probably one that has teh shape of a bullet at first. so i guess you could say it is harpooning, but the harpoon has a much smaller mass and the fring mechinisim is probably jsut a gun with a spoke on it. shooting into a plane may not be a very good example lol, you miht just bring the plane down instead of bring you up lol.

  10. Jan 17, 2005 #9


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    The short answers are: yes and yes. A line tied to the back of a projectile will slow it down, and will affect its trajectory.

    Now, the next question is: by how much?

    Well, there are some devices of various sizes that do this. A harpoon being the most obvious. But there are others, I think wire-guided missiles use it. So do ranged tasers.

    You want to maximize the mass of the projectile while minimizing the drag of the wire. BTW, the drag is probably due as much to the mass of the line as it is to the friction involved in unspooling.
  11. Jan 17, 2005 #10


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    Actually, for a spool carried with the projectile, friction when unspooling (manifest as tension on the wire) is all of the force seen: there is no aerodynamic drag, since the wire behind the projectile is stationary.

    Mass of the wire is a double-edged sword: it increases the momentum of the projectile, which decreases the effect of the tension force, but it also increases the force needed to pull it off of the spool. It probably cancels out completely.
  12. Jan 17, 2005 #11
    ok, well this was interesting, onto the designs!

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