the speed of sound

[funkymoped]

the americans broke the sound barrier at around 660mph in the air.

Britain broke the sound barrier at 763mph on the ground with Thrust SSC.

why is there NO set speed for sound ? even on the day Thrust set the record, his speed could have been faster or slower and still have broken the sound barrier. i know its partly to do with atmospheric pressure and moisture in the air, but i cant work the maths !

[sddsddean]

It's not easy. You can google for equations to give the speed for a various parameters. Basically the denser a medium is, the faster the speed of sound. In air at sea level its about 700mph. At higher altitudes the air is less dense, so its slower. Put a bit of moisture in the air (increase density), it will increase. For a totally 'wet' environment, the speed in water is about 3500mph.

[funkymoped]

i think above 36,000ft the speed of sound is constant. i know these things can be looked up on the net but brain power works better for me.

thanks lads, appreciated.

[fo3nix]

It's never constant, except for in a pure vacuum. But many times it can pretty much be taken as constant, without much change in the stuff you're trying to work out.

wikipedia gives a good explanation:
http://en.wikipedia.org/wiki/Speed_of_sound

[gen2]

May I just correct an error in what sddsddean has stated above. Adding moisture to air actually DECREASES its density. For every molecule of water that is added, one molecule of oxygen or nitrogen will be displaced. Water (H2O) has a molecular weight of 18, Oxygen (O2) = 32 and nitrogen (N2) = 28.

[George38]

Sound needs a medium in which to travel (air, water etc). since there is no such medium present in a pure vaccuum, the speed of sound is surely zero (I suppose that counts as a constant!!).

[fo3nix]

precisely :)

[rugeleyboy]

errr??

[mibn2cweus]

OUCH!

[phaloides]

There was young fellow from Staines
Who is searching with infinite pains
For a new kind of sound
Which he hopes when it's found
Will travel much faster than planes.