Question

An example to show light travels faster than sound

Answer 1

Light ans sound are two very different things.

Light

Light can be either seen as an electromagnetic wave or as a photon… In any case light is massless, since photons have no mass. In the “wave picture” light does NOT require a medium to carry the wave, since the wave is simply an oscillation of an electric and magnetic field perpendicular to each other. (When quantum mechanics come into play we realize that the picture is somewhat in between these two, but never mind that for now)

In any case following the wave picture that arises from Maxwell’s equations we can get the speed of light by solving a wave-equation based on Maxwell’s equations (here is a workout of it: Maxwell's Equations. From Einstein Light).

In the particle view, massless particles MUST have the speed of light according to relativity (Francesco Maddalena's answer to Is it E=PC or E=p^2/2m?)

Of course these two pictures are just two equivalent views of the same thing.

Sound

Sound, in air, liquids or solids is basically waves carried by those particles.

Basically these waves are “compression waves” (usually) where the molecules/atoms compress towards each other or stretch away from each other as seen in the picture below.