• Introduction
• Lesson
• Try It!
• Review & Tasks

Basics of Sound

Sound waves travel through air at a relatively constant speed — approximately 350 m/s.  It travels through water almost 5 times faster – 1500 m/s, and even faster through solid materials like brick.  This is because sound is a mechanical wave and must travel through a mediumthe matter mechanical waves travel through.  Sound cannot travel though empty space because there are not enough particles to bump together to transfer the sound energy along. 

At 330 m/s, how long does it take sound to travel 1 km in air? 

s = d/t

1000 m / 330 = 3.03 seconds. 

1 mile is about 1.6 km, so it takes sound about 4.84 s or about 5 seconds to travel one mile. 

If you see a flash of lightning in the distance and it takes the sound of thunder 5 seconds to reach you, the lighting was about one mile away.  When you see a flash of lightning, count slowly and stop when you hear the thunder.  Divide the seconds you counted by 5 to determine the distance to the lightning.

Image courtesy of flickr user samwiseat01. This image is protected by a Creative Commons Attribution-Noncommercial 2.0 Generic license.