# speed of sound

## what is the speed of sound

The speed of sound is the distance that sound waves travel in a given amount of time. Youll often see the speed of sound given as 343 meters per second. But thats just the speed of sound under a certain set of conditions, specifically, through dry air at 20 C. The speed of sound may be very different through other matter or at other temperatures.

## speed of sound in different media

Sound waves are mechanical waves, and mechanical waves can only travel through matter. The matter through which the waves travel is called the medium (plural, media). The Table 1.1 gives the speed of sound in several different media. Generally, sound waves travel most quickly through solids, followed by liquids, and then by gases. Particles of matter are closest together in solids and farthest apart in gases. When particles are closer together, they can more quickly pass the energy of vibrations to nearby particles. Medium (20 C) Dry Air Speed of Sound Waves (m/s) 343 Medium (20 C) Water Wood Glass Aluminum Speed of Sound Waves (m/s) 1437 3850 4540 6320 Q: The table gives the speed of sound in dry air. Do you think that sound travels more or less quickly through air that contains water vapor? (Hint: Compare the speed of sound in water and air in the table.) A: Sound travels at a higher speed through water than air, so it travels more quickly through air that contains water vapor than it does through dry air.

## temperature and speed of sound

The speed of sound also depends on the temperature of the medium. For a given medium, sound has a slower speed at lower temperatures. You can compare the speed of sound in dry air at different temperatures in the following Table 1.2. At a lower temperature, particles of the medium are moving more slowly, so it takes them longer to transfer the energy of the sound waves. Temperature of Air 0 C 20 C 100 C Speed of Sound Waves (m/s) 331 343 386 Q: What do you think the speed of sound might be in dry air at a temperature of -20 C? A: For each 1 degree Celsius that temperature decreases, the speed of sound decreases by 0.6 m/s. So sound travels through dry, -20 C air at a speed of 319 m/s.

## instructional diagrams

No diagram descriptions associated with this lesson

## questions

the speed of sound is faster than the speed of light.

``````a. true

-->  b. false
``````

sound waves can travel only through matter.

``````-->  a. true

b. false
``````

sound waves generally travel most quickly through

``````a) gases.

b) liquids.

-->  c) solids.

d) plasma.
``````

sound waves travel more quickly through dry air than moist air.

``````a. true

-->  b. false
``````

the speed of sound through air is fastest when the air temperature is

``````a) 0 c.

b) 20 c.

c) 40 c.

-->  d) 60 c.
``````

## diagram questions

No diagram questions associated with this lesson