Waves—I

How could the submarine’s depth be determined from measurements made very far away?

The answer is in this lesson.

In August 2000, as Russia’s Northern Fleet conducted exercises in the Barents Sea north of Russia, the nuclear submarine Kursk mysteriously sank. As word of the loss spread, seismologists from around the Northern Hemisphere realized that, on the day the Kursk sank, they had recorded unusual seismic waves originating in the Barents Sea. Analysis of the data suggested the reason the submarine sank, and—more surprising— it also revealed its depth.

What Is Physics?

One of the primary subjects of physics is waves. To see how important waves are in the modern world, just consider the music industry. Every piece of music you hear, from some retro-punk band playing in a campus dive to the most eloquent concerto playing on the Web, depends on performers producing waves and your detecting those waves. In between production and detection, the information carried by the waves might need to be transmitted (as in a live performance on the Web) or recorded and then reproduced (as with CDs, DVDs, or the other devices currently being developed in engineering labs worldwide). The financial importance of controlling music waves is staggering, and the rewards to engineers who develop new control techniques can be rich.

This lesson focuses on waves traveling along a stretched string, such as on a guitar. The next lesson focuses on sound waves, such as those produced by a guitar string being played. Before we do all this, though, our first job is to classify the countless waves of the everyday world into basic types.