How many feet per second is the speed of sound?

[blackops]

So when a sniper that is engaging a target at 1500yds the target is going to hear the shot for a split second before the bullet makes impact?

 

[R.W.Dale]

So when a sniper that is engaging a target at 1500yds the target is going to hear the shot for a split second before the bullet makes impact?

At 1500 yds with a rifle capable of doing so the sound wave will arrive a lot later than "a split second"

 

[cottonmouth]

1,100 fps........... so how may miles per hour is that!

J.B.

 

[MachIVshooter]

First, it is better to start a new thread with this question than dig up a three year old one. Now:

So when a sniper that is engaging a target at 1500yds the target is going to hear the shot for a split second before the bullet makes impact?

No. Even if the round does go subsonic by the time it gets there, the sound wave will not catch up to it. A good round average number for rifle bullets the likes of which would be employed for hunting, be it people or big game animals, is ~3,000 FPS, which is nearly mach III.

 

[Tommygunn]

1,100 fps........... so how may miles per hour is that!

750 miles per hour

 

[Furncliff]

Nat. Wx Svc Speed of Sound Calculator.

http://www.srh.noaa.gov/elp/wxcalc/speedofsound.shtml

 

[twofifty]

quote: "the reason you want a supersonic bullet ot stay supersonic is to keep it from passing through the shock wave. a supersonic projectile has a shock wave traveling BEHIND it. if the bullet slows down to subsonic velocities it passes through the shockwave which can alter its course slightly."

Interesting.

I wonder if this now sub-sonic bullet isn't actually overtaken by its own supersonic shock wave, which would disrupt it from the rear, introducing yaw?

otoh, a bullet slows down throughout its flight... So the shock wave ought to overtake the bullet, even a varmint round that starts out at Mach 3+. The speed of sound is a condition dependant constant, but the speed of the shock wave's travel through the air is co-related to bullet velocity.

Since all bullets slow down, all shock waves ought to catch up to them, over and over again, no?

Someone help me out here. lol.

 

[Acera]

Result: 1116 ft/s (feet per second)

Some other calculations to amuse you on the speed of sound.

~~ 340.3 m/s (meters per second)
~~ 0.3403 km/s (kilometers per second)
~~ 0.2115 mi/s (miles per second)
~~ 12.69 mi/min (miles per minute)
~~ 761.2 mph (miles per hour)
~~ 20.42 km/min (kilometers per minute)
~~ 29400 km/day (kilometers per day)
~~ 661.5 knots

Slowness from S=1/v: 0.0029 s/m (seconds per meter)



You guys have to learn the value of Wolfram/Alpha. All of this type of stuff is easily calculated by the most basic of inputs. Here is the link for this calculation.

http://www.wolframalpha.com/input/?i=speed+of+sound+in+feet+per+second+


If you don't know about it, check it out and watch some of the introduction videos, it's amazing.

 

[robmkivseries70]

Another constant, roughly speaking: 88 f/s = 60 mph.
Best,
Rob

 

[blackops]

You would think that at 3000yds you would hear it for an instant before it made contact.

 

[Uncle Mike]

1,100 fps........... so how may miles per hour is that!

That's about how fast my old Ford will go...no, wait...I think it's 1,100 SPF!

Don't get too hung up on the transonic barrier thing, true a bullet will experience buffeting transitioning this barrier however this does not mean the projectile becomes permanently unstable or permanently displaced for the remainder of its journey.

The projectile may experience buffeting which may cause longitudinal and or lateral displacement... but if the projectile is uniform and it had departed with the proper stabilizing centrifugal inertia (proper twist rate) then the bullet possesses positive static stability... meaning it will return to its original position after being disturbed...given enough room between the transonic barrier and the target.

Good bullets are said to posses excellent dynamic stability also...meaning that not only does the bullet want to, and makes an effort to, return to its original position after being disturbed(Positive Static Stability)...but it will accomplish this in decreasing cycles (it will return to its original position quickly).

So, just because your 22MAG bullet goes 'slowsonic', does not necessarily mean that your going to become inaccurate all of a sudden.

 

[jakemccoy]

Off topic... The rough speed of sound is a good thing to know during a lightning/thunder storm, to figure out how far the last lightning strike was away.

 

[ScottG1911]

Speed of sound is dependent on a bunch of other variables like temperature and humidity, but ~340m/s is a good number for napkin math.

Exactly correct. in fact I can still remember from my freshman science book, that sound travels at 324M/s at 20 degrees C. at sea level. so you're looking at 1050fps at 62 degrees F. and it will increase speed with increased temp. and decrease with altitude

 

[hammerklavier]

The speed of sound most certainly is dependent on the air pressure, or as NOAA puts it, the density of the air. However, since pressure and temperature in an open system are related, you can make a simplified formula that uses just the temperature. If you were to measure the speed of sound inside a compressed air tank, you'd find it does make a difference apart from temperature.

 

[mec]

Whatever it is the speed of sound can get interesting with certain reloads. Get a load that straddles it and some rounds will go pop while others go crash. I sounds like some seriously inconsiistency taking place but, over the chronograph, the velocities can actually be very close together.

 

[matrem]

Another constant, roughly speaking: 88 f/s = 60 mph.

That's not rough, that's exact.
There are 5280 feet in a mile.
There are 3600 seconds per hour.
Each - divided by 60.