# Speed of Sound (warm air or cold air)

1. Dec 11, 2010

### anna sung

1. The problem statement, all variables and given/known data

I am so confused with speed of sound. would sound travel faster in cold or warm air?
if you put mathmatical equation in, v= 331 + (0.59Tc) then it would travel faster in warm air.
but another theory says that sound travels faster in denser medium and cold air is denser than warm air, hence it travels faster in colder air. it it true?

And at night over water we can hear sound clearly on shore than during the day because of colder air during night and over water, as cold air is dense, molecules can bump into each other better as they are closer, makes it travel faster? or the speed of it has nothing to do with it? would the answer be just (it travels better because it is denser)?

2. Dec 11, 2010

### Staff: Mentor

More likely at night over water, there is less background noise, so one can hear more clearly, but the speed of sound is not increased.

http://hyperphysics.phy-astr.gsu.edu/hbase/sound/souspe.html
http://hyperphysics.phy-astr.gsu.edu/hbase/sound/souspe3.html

The speed of sound (in a gas) is inversely proportional to M1/2, where M is the molecular (or atomic mass for monatomic (noble) gases), and that of course is related to density. On the other hand, the speed of sound increases with temperature even as density decreases slightly.

3. Dec 11, 2010

### anna sung

yes but if you were to explain using physics how would you explain that at night over water u can hear sound clearly than during the day?

4. Dec 11, 2010

### moondawg

As temperature increases, air particles move more, and allow for better propagation of sound waves