waves

[einsteinsdog]

why is the speed of propagation of a surface wave considerably different to that of a sound wave in the same medium?

[NiceCupOfTea]

I'm not a physicist, but it may be because with a sound wave a molecule is just being vibrated, whereas with a surface wave the molecule is being physically displaced. I need to know the answer too now - come on physics people!

[fo3nix]

Yea, I'd say that NiceCupOfTea is right.

It's the difference between transverse waves and longitudinal waves. Sound is a longitudinal wave, and as such, the particles are physically displaced across the medium (left to right, let's say). Transverse waves take one particle at a time, moving that particle up and down, followed by the next (like a Mexican wave), but the particles do not actually move across the medium (not left and right).

A surface wave is a mix of the above two, and so the speed of propogation is slowed down with the "transverse" component of the wave.