A swimming fish seems to glide through the water without making a sound. But it doesn’t swim as quietly as you think. Divers swimming underwater hear a loud crack when a large fish flips its tail and darts away.
Most of the everyday sounds we hear travel through air. But sound waves travel through liquids and solids, too. Things like water, wood, and even the earth can conduct, or carry, these vibrations. You know this is true if you’ve ever heard noise coming from a closed room. Sound travels through walls and doors.
The molecules of liquids and solids are closer together than the molecules in air. And in some liquids and solids, the molecules are “springy”. They bounce back like a rubber band when they are pushed.
These kinds of molecules vibrate easily when a sound wave pushes them. And they make nearby molecules vibrate, too. So in a solid or liquid with “springy” molecules, sound travels even faster than it travels through air.
A loud sound takes about 5 seconds to reach you if it travels 1.5 kilometres through air. But underwater, the same sound reaches you in little more than a second. And a sound wave zips through 1.5 kilometres of steel wire in about 1/3 second. This is almost 15 times faster than it travels through air.
Picture Credit : Google
