Velocity of Sound.
How fast do the waves of sound move through the air?
They move at the rate of ten hundred and ninety feet in a second of time, when the temperature of the air is thirty-two degrees.
What effect does warm air have on sound?
Sound travels more rapidly in warm air.
How much does heat increase the velocity of sound?
The velocity of sound is increased one foot in a second of time, for every degree of heat added to the air; so that sound travels eleven hundred and twenty feet in a second, when the temperature is at sixty-two degrees, which is nearly one mile in five seconds.
Does light travel more rapidly than sound?
Yes; light comes from the moon to the earth, a distance of two hundred and forty thousand miles, while sound moves eleven hundred and twenty feet.
What familiar examples of this difference may be given?
A wood-chopper’s axe is seen to descend before we hear the stroke, and the smoke from a gun is seen before we hear the report.
How can we tell the distance of the wood-chopper from us?
If we count the number of seconds between the stroke of the axe and the time when the sound reaches our ear, and multiply eleven hundred and twenty by this number, it will give us the distance in feet; because sound travels eleven hundred and twenty feet in a second.
How can we tell the distance of lightning from us?
If we count the number of seconds between the lightning and the thunder, and divide this number by five, it will give the distance in miles; because sound travels one mile in every five seconds.
How rapidly does sound travel through water?
Sound travels about four times as rapidly through water as it does through air.
How rapidly does sound travel through a solid?
Sound travels ten times as rapidly through wood, and sixteen times as rapidly through glass, as it does through air.
Does a loud sound travel more rapidly than a faint one?
No; it does not.
How do we know this?
Because the notes from a band of music come to us in the order in which they are played, whether they are loud or faint.