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Speed of Sound
Posted: Fri Nov 25, 2011 10:14 am
by Tower75
Ok. Here's something that might make you go "Hmmm...", I did.
The speed of sound is 343.2 metres per second. Right?
So, the question is, when I'm pulling targets at the 600 yard line (548.64 metres) why do I hear the report of the rifle as soon as I see the sand splash?
As the SoS travels at 343.2 mps, shouldn't it take 1.59 seconds for the rifle's report to reach me?
For the sake of argument, lets take the 174gr .303 MkVII cartridge, that thing travels at about 760 metres per second, so it's not even the case where the bullet is taking 2 seconds to reach me.
Shouldn't it be;
[splash] one-one thousand... two one thousa - [crack] ?
Re: Speed of Sound
Posted: Fri Nov 25, 2011 10:30 am
by rox
Tower.75 wrote:So, the question is, when I'm pulling targets at the 600 yard line (548.64 metres) why do I hear the report of the rifle as soon as I see the sand splash?
Shouldn't it be;
[splash] one-one thousand... two one thousa - [crack] ?
Isn't the 'crack' the sonic boom of the bullet passing overhead, rather than the report of the rifle?
..
Re: Speed of Sound
Posted: Fri Nov 25, 2011 10:31 am
by ovenpaa
The time of flight to the 600 yard point is going to be around 0.838 seconds, add another 20 yards to the sand and ToF is approaching one second so your ears need to detect two cracks in around half a second, possible but given your position it is easy to confuse the sounds as one.
Well that is my theory :)
Re: Speed of Sound
Posted: Fri Nov 25, 2011 11:21 am
by Sandgroper
rox wrote:Tower.75 wrote:So, the question is, when I'm pulling targets at the 600 yard line (548.64 metres) why do I hear the report of the rifle as soon as I see the sand splash?
Shouldn't it be;
[splash] one-one thousand... two one thousa - [crack] ?
Isn't the 'crack' the sonic boom of the bullet passing overhead, rather than the report of the rifle?
..
Yes. In the forces we were taught to use the "crack" of the round passing overhead/nearby with the "thud" of the rifle that fired it, to estimate range. Fine in theory (or in the butts) but below 300m the "crack/thud" was virtually simultaneous.
Re: Speed of Sound
Posted: Sat Nov 26, 2011 5:41 pm
by Tower75
All good points. That explains it. Cheers, guys.
Re: Speed of Sound
Posted: Mon Nov 28, 2011 7:30 pm
by meles meles
Not to mention the complicating factor that oomans have large brains. That matters. By the time the auditory signal has travelled from your ears to the cerebral cortex and been processed quite a significant additional time has elapsed. That's why badgers and other small brained creatures are smarter than oomans. We can think faster because our thoughts travel shorter distances through less cluttered brains...
Re: Speed of Sound
Posted: Mon Nov 28, 2011 8:36 pm
by 1066
Can you actually hear a rifle shot from 600 yds when you are in the butts? (I'm usually like a coiled spring waiting for the splash in the sand :) )
Re: Speed of Sound
Posted: Mon Nov 28, 2011 8:45 pm
by meles meles
1066 wrote:(I'm usually like a coiled spring waiting for the splash in the sand :) )
Yes, those cold winds and the flask of coffee can play havoc with the bladder...
Re: Speed of Sound
Posted: Mon Nov 28, 2011 9:51 pm
by Robin128
Only have to run a tap near me these days.
:-P
Re: Speed of Sound
Posted: Tue Nov 29, 2011 6:34 am
by 1066
meles meles wrote:1066 wrote:(I'm usually like a coiled spring waiting for the splash in the sand :) )
Yes, those cold winds and the flask of coffee can play havoc with the bladder...
:lol: :lol: :lol: