IIT JEE , AIEEE Forum - Physics , Mechanics

anshulnigam

plz tell that the velocity of sound would be large in dry or humid air?

y=Asin(kx-wt)& y=3Asin(kx+wt) when superimpose each other then what is the resultant inference?

kaushalsapre

Hi,
Velocity of sound will be higher in humid air because humidity decreases the density of air. By the relation-
v =

P/

Density(

) decreases and v increases

bubun

Velocity of sound is sqrt(elastic modulos/density) . Molecular mass of dry air is 28.8 and that of water vapour is 18 . So moist air has MM >18 and <28.8 . So its density is less and hence velocity of sound is more in moist air

edison

The speed of sound depends on wind conditions, temperature, and humidity.
It does not depend on the frequency of sound; all notes travel at the same
speed. The speed of sound in dry air at 0 degrees C is about 330 meters per
second, nearly 1,200 kilometers per hour. Water vapor in the air increases
this speed slightly. Sound travels faster through warm air than through
cold air. This is to be expected because the faster-moving molecules in
warm air bump into each other more often and therefore transmit a pulse in
less time. For each degree rise in temperature above 0 degrees C, the speed
of sound in air increases by 0.6 meters per second. In water, sound travels
about four times as fast as it does in air, while in steel, the speed of
sound is about fifteen times as great as in air.

cvramana

1. Speed of sound is more in humid air because the molecular mass of humid air is less than that of dry air.

2. The resultant wave of the two waves

y= A Sin (wt - kx) and y= 3A Sin(wt + kx) is

y= A Sin wt cos kx - A Sin kx cos wt + 3A Sin wt cos kx + 3A Sin kx Cos wt.

Y=4A Sin wt Cos kx + 2A Sin kx Cos wt

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