The Speed of Sound

Sound travels much slower than light. In air at room temperature, sound moves at about 767 miles per hour. That is fast, but light is about 870,000 times faster. The speed of sound changes depending on what it travels through. It moves faster in water and even faster in solid materials.

What Affects the Speed of Sound

Sound travels at different speeds in different materials. In air, it moves at about 767 miles per hour. In water, it moves at about 3,350 miles per hour. In steel, it moves at about 11,000 miles per hour. Sound is faster in denser materials because the molecules are closer together and pass vibrations along more quickly.

Breaking the Sound Barrier

When an aircraft flies faster than the speed of sound, it is called supersonic flight. The aircraft pushes through the air faster than sound waves can move ahead of it. This creates a shock wave that people on the ground hear as a loud sonic boom. Chuck Yeager was the first person to break the sound barrier in 1947.

Fun Facts

• The speed of sound in air increases about 1.1 miles per hour for every degree Fahrenheit the temperature rises.
• The Concorde was a supersonic passenger plane that could fly at over 1,300 miles per hour.
• A cracking whip makes a snapping sound because the tip moves faster than the speed of sound.

Did You Know?

You can see that light is faster than sound at a baseball game. If you sit far from the field, you see the batter hit the ball before you hear the crack of the bat. The light reaches your eyes almost instantly, but the sound takes a moment longer!