How Fast Does Sound Travel Per Second?

How Fast Does Sound Travel Per Second?

Have you ever noticed a delay between seeing a lightning flash and hearing the thunderclap? That familiar gap exists because light travels almost instantly, whereas sound takes its time journeying through the air.

Under standard conditions, the speed of sound in dry air at room temperature (20°C or 68°F) is roughly 343 meters per second.

Breaking Down the Numbers

Depending on the units you prefer, that single second of travel covers quite a bit of ground:

• Meters: 343 meters per second
• Kilometers: About 1,235 kilometers per hour
• Miles: Roughly 767 miles per hour
• Feet: About 1,125 feet per second

When an aircraft travels faster than this benchmark, it breaks the sound barrier, creating a dramatic sonic boom.

What Changes the Speed of Sound?

Sound isn’t a universal constant; its pace changes depending on what it is traveling through and the surrounding environment.

• Temperature: Sound waves love warmth. As air temperature rises, air molecules move faster and pass vibrational energy along more quickly. For every degree Celsius the temperature increases, the speed of sound picks up by about 0.6 meters per second.
• The Medium: Sound travels fastest through solids, followed by liquids, and slowest through gases. While it moves at 343 meters per second in air, it tears through water at roughly 1,481 meters per second, and rockets through iron at over 5,100 meters per second because tightly packed particles transfer sound energy much faster.

The Classic Thunder Trick

You can use the speed of sound in the real world to estimate how far away a storm is. Because sound travels roughly one kilometer every three seconds (or one mile every five seconds), you can simply count the seconds between seeing lightning and hearing thunder, then divide by three to find the distance in kilometers.

343 m/s Explained video

This video provides a helpful visual breakdown of why sound travels at 343 meters per second and the key environmental factors that influence its speed.
http://googleusercontent.com/youtube_content/1