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Thread: supersonic crack

  1. #1

    supersonic crack

    does a bullet of larger calibre make a louder crack than a smaller calibre bullet given a velocity and weight about the same

    regards pj

  2. #2
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    In theory, yes - think of the noise an aeroplane makes (if you've ever heard it) - they don't call it a supersonic 'boom' for nothing! If you look up Sonoc Boom on Wikipedia - Sonic boom - Wikipedia, the free encyclopedia - it gives you a very detailed explanation, but in essence the loudness is determined directly by the size of the missile and how fast it is travelling.

    Geek mode over. HTH

    E t R
    Nooooooooooooobody expects the Spanish Inquisition!! Our main weapon is.........

  3. #3
    thanks E t R. have just thought of that whilst washing up. i suppose that teaches me. i should do the chores and think about these things before asking away. and yes i have heard planes breaking the sound barrier so it should of been obvious shouldnt it

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    Noone should ever be ashamed or put down for asking an honest question - it's how we learn. As someone far wiser than me once said - there's no such thing as an easy or a hard question; there are just those you know the answer to...and those you don't!

    Your question was more subtle than at first glance - you'd already identified the two main components of momentum (mass and velocity) as being the same, so you'd done the hard work! Surface area (overall size and density) is therefore pretty much the only variable left. I think it's a good question. The reality of it is that it is highly unlikely you would detect much of a difference in volume between bullets as the difference in surface area is small and Decibels are a logarithmic scale. Oops, back to geek mode....
    Last edited by Eric the Red; 14-04-2011 at 22:41. Reason: Smelling
    Nooooooooooooobody expects the Spanish Inquisition!! Our main weapon is.........

  5. #5
    I shoot a bit at the range, when in the butts pulling targets its impossible to tell what caliber is being shot at my target or even if the rifle is moderated or not, the super sonic crack sounds just the same weather 223 or 308, moderated or not, the only give away is the size of hole in the target

    mike

  6. #6
    surely momentum isnt a factor, just velocity and surface area?
    mass should not be a factor.
    In theory you could have a spire point or conical point bullet of a larger calibre producing a similar effect to one with a round nose. but I suspect the difference would not be audible!
    Last edited by bewsher500; 15-04-2011 at 08:24.

  7. #7
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    At one of the ranges I shoot at they shoot calibres from .223 to .338 Lapua at 800 yds you can't hear the muzzle blast just the super sonic crack
    sometimes I can pick the .223's but the others all sound the same, would need some very hi tech test gear to measure the difference.

  8. #8
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    Quote Originally Posted by bewsher500 View Post
    surely momentum isnt a factor, just velocity and surface area?
    weight should not be a factor.
    In theory you could have a spire point or conical point bullet of a larger calibre producing a similar effect to one with a round nose. but I suspect the difference would not be audible!
    ...opportunity for more geek mode....(sorry).....

    The mathematical equation to express momentum (p) equals 0.5mv^2 (squared), where (m) is mass and (v) is velocity. Weight is a force and is defined by the equation mg where (m) is mass and (g) the acceleration applied by gravity.

    The point I'm trying to make (very poorly) is that we are both right. Even more bizarrely, the faster the object travels over Mach1, the boom lessens off again, to the extent that at very high speeds the boom is no longer heard.

    Useless fact of the day - the crack of a bullwhip is a mini supersonic crack, and was man's first crossing of the sound barrier.
    Nooooooooooooobody expects the Spanish Inquisition!! Our main weapon is.........

  9. #9
    Quote Originally Posted by Eric the Red View Post
    ...opportunity for more geek mode....(sorry).....

    The mathematical equation to express momentum (p) equals 0.5mv^2 (squared), where (m) is mass and (v) is velocity. Weight is a force and is defined by the equation mg where (m) is mass and (g) the acceleration applied by gravity.

    The point I'm trying to make (very poorly) is that we are both right. Even more bizarrely, the faster the object travels over Mach1, the boom lessens off again, to the extent that at very high speeds the boom is no longer heard.

    Useless fact of the day - the crack of a bullwhip is a mini supersonic crack, and was man's first crossing of the sound barrier.
    ha ha, touche.
    edited for accuracy (schoolboy error mixing mass and weight!)

  10. #10
    thanks guys very interesting. the thought came to mind originally as i use a .22 lr a fair bit for rabbits but get ricochet off of hard ground so thought of getting a .17 hmr or .22 wmr and didnt know if the larger .22 would be much louder than the .17.

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