Dear Sellerwithintegrity,
Waves can be divided into two categories: mechanical and electromagnetic. The very nature of this classification is that electromagnetic waves can propagate in a vacuum. You are correct that sound waves are not like light waves, although we lost the "ether" some time back ;-), but they are waves, and share some fundamental characteristics.
Another categorization of waves is into longitudinal waves (such as sound waves), transverse waves (where the disturbed particles vibrate perpendicular to the direction in which the waves move), and surface waves (where the particles undergo circular motion).
Let me give you another example of a wave to demonstrate that the individual particles don't in fact move. You are at a big football game, and the "wave" is started by the boisterous beer drinkers in section B. They jump up, hands in the air, and sit down. Observed by their neighbours, who at the right moment jump up ... and so it goes. Watching from the Goodyear blimp, we observe the wave travel around the stadium a few times until it dies out through boredom. But the lads in section B are still there. They didn't run around the stadium with their hands in the air, did they? No, they have to stay in the cheap seats.
Regards,
Sound involves the actual movement of air molecules.The air molecules only vibrate. Each individual particle of the medium (air) is temporarily displaced and then returns to its original equilibrium position.
Waves can be divided into two categories: mechanical and electromagnetic. The very nature of this classification is that electromagnetic waves can propagate in a vacuum. You are correct that sound waves are not like light waves, although we lost the "ether" some time back ;-), but they are waves, and share some fundamental characteristics.
Another categorization of waves is into longitudinal waves (such as sound waves), transverse waves (where the disturbed particles vibrate perpendicular to the direction in which the waves move), and surface waves (where the particles undergo circular motion).
Let me give you another example of a wave to demonstrate that the individual particles don't in fact move. You are at a big football game, and the "wave" is started by the boisterous beer drinkers in section B. They jump up, hands in the air, and sit down. Observed by their neighbours, who at the right moment jump up ... and so it goes. Watching from the Goodyear blimp, we observe the wave travel around the stadium a few times until it dies out through boredom. But the lads in section B are still there. They didn't run around the stadium with their hands in the air, did they? No, they have to stay in the cheap seats.
Regards,