Do elastic properties fail at really high velocity?

Discussion in 'Physics & Math' started by GeoffP, Mar 20, 2010.

  1. GeoffP Caput gerat lupinum Valued Senior Member

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    Like if you bounced a ball off something really fast. I just feel that hitting something too hard would kind of squash the ball and lose the elasticity that you generate bounce from.
     
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  3. Neverfly Banned Banned

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    I would use the word, "Overwhelm."

    The force of impact would overwhelm the elasticity of the ball.

    Of course, you could also horribly freeze said victim ball and THEN smash it at less speed...

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  5. GeoffP Caput gerat lupinum Valued Senior Member

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    Ah, I see. Thanks!
     
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  7. Neverfly Banned Banned

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    No way it was that easy.

    I'm not smart.

    Ask it again, but do it better this time so I can say, "Damn,, umm you know... I have no idea...

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  8. GeoffP Caput gerat lupinum Valued Senior Member

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    I would if I could, but I'm no physicist. I actually just wanted to know if it was possible...but not for unspecified military applications in East Korea. Not. Like if someone wanted to bounce a giant ball off the earth and have it hit near-orbit, then come crashing down on New York unless they paid you one triiiillllion dollars!

    But that's not happening, because that would just be crazy.

    Carry on, citizen!
     
  9. Neverfly Banned Banned

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    Damn,, umm you know... I have no idea...

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    Yes, that would be. You're better off building a Giant "Laser" on the Moon and pointing it at Washington and demanding 1 BILLION Dollars.


    ETA: Essentially, the physical structure of the ball would break down before elasticity could compete with the force.
    It's a bit like putting your finger in the muzzle of a firearm. If the firearm is then fired, the bullet moves so quickly that in spite of impacting on the fingertip- the fingertip doesn't have Time to be pushed out of the way. This results in blow back in the chamber.

    As a last resort, we are taught in the military to do this if death is imminent and you are at close enough range. You'll lose your hand but the gunman will lose his life.
     
  10. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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    Er, wouldn't an APFSDS round be a good illustration of that?
    Silly GeoffP.

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  11. kurros Registered Senior Member

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    Most materials will undergo elastic deformation only up to a certain point, after that that deform plastically (i.e. permanent changes in their structure occur), or they will just fail totally (brittle materials often just shatter without undergoing any (well not much) plastic deformation).

    Really? What kind of firearms? The barrel of a standard 5.56mm rifle isn't big enough to stick your finger down, even 7.62mm is still too small, although you can usually get it in the flash suppressor if it has one (I can't imagine this helping much

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    ). Or is it enough to just kind of block it off a little? A shotgun barrel is big enough I guess but the military don't tend to use those.
     
  12. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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    South African 20mm P.A.W.?

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    They do*. They even commission special ammo for them.

    * At minimum - Russia, USA, UK.
     
  13. Neverfly Banned Banned

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    You're right, I worded that badly. Better wording would be to cover the muzzle with your fingertip.
    The firearms in question are of course handheld pistols.

    Since rifles are used long distance, there is a slim chance that a person would be close enough that you could touch the weapon without having shot you. Plus, the flash suppressor would blow it out the sides of the muzzle.

    Commonly, pistols end up being placed against the head or neck. They rarely have a flash suppressor.
     
  14. MacGyver1968 Fixin' Shit that Ain't Broke Valued Senior Member

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  15. Neverfly Banned Banned

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    Probably had jammed his muzzle into the dirt and didn't check it. He's lucky.
     
  16. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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    Or an (invisible) Bugs Bunny had his finger on the muzzle.

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  17. Neverfly Banned Banned

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    If he was invisible, I'd worry about that wascawy wabbit sticking something else in there.
     
  18. kurros Registered Senior Member

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    Hmm, fair enough, I never would have thought that would be enough but I'll believe you. Surely this suggests it's a really bad idea to place the pistol right up against the head or neck if you intend on firing it. Aside from the other obvious issues with being that close to a hostile individual while holding a firearm.
     
  19. Neverfly Banned Banned

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    Essentially, whatever object is blocking the muzzle, it simply doesn't have time to get out of the way should the firearm be discharged.

    Very true. And how often would that happen?
    But if it DID, and if the situation went from hostile or threatening (Capturing) to desperate (Awww screw it. Gonna kill this guy--A situation that was intended at first to be intimidation could turn lethal should the enemy spook.) then you know you have options to prevent death itself.

    ETA: A friend just pointed out that with current military activity involving terrorist suppression, there's more of a push due to Execution style videos trying to be made, etc. Said terrorist has captured a soldier, pokes him with pistol self confidently, makes speech... Oops. In accordance with the soldiers creed- Anything to throw a monkey wrench in the works.
     
    Last edited: Mar 21, 2010

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