Factors Affecting Speed of Sound in Gas-

 

The speed of sound in any gaseous medium is affected by a large number of factors like density, pressure, temperature, humidity, wind velocity etc.

 

In this article, we will discuss all these factors one by one.

 

Effect of Density-

 

The speed of sound in a gaseous medium is given by-

 

Clearly, the speed of sound in a gas is inversely proportional to the square root of density of the gas.

 

For two gases at same pressure, we have-

 

 

Effect of Pressure-

 

The speed of sound in a gaseous medium is given by-

 

Substituting ρ = M / V, we have-

At constant temperature, PV = constant.

 

Thus, the speed of sound is independent of the change in pressure of the gas as long as temperature remains constant.

 

This happens because effect of change in pressure is completely nullified by the corresponding change in density of the gas at constant temperature.

 

Effect of Temperature-

 

The speed of sound in a gaseous medium is given by-

 

Using P = ρRT / M_o, we have-

where M_o = Molar Mass of Gas

 

Clearly, the speed of sound in a gas is directly proportional to the square root of its absolute temperature.

 

Hence, sound travels faster on a hot summer day than on a cold winter day.

 

Effect of Humidity-

 

The speed of sound in a gaseous medium is given by-

 

The presence of water vapors in air changes its density. The density of moist air is less than that of dry air. So, as humidity (as in rainy season) increases, the speed of sound increases.

 

Thus, the speed of sound in moist air is greater than the speed of sound in dry air.

 

Hence, sound travels faster on a rainy day than on a dry day.

 

Test Your Concepts-

Factors Affecting Speed of Sound in Gas

 

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