When an object vibrates, it produces sound. Sound can only travel through a medium, such as via a solid, liquid or gas.
Sound waves are longitudinal, which means that the vibrations are parallel to the direction of wave travel. This is why sound waves show periods of compression and rarefaction.
Loudspeakers work by producing kinetic energy from electrical energy.
When the speaker produces sound:
1. The speaker skin oscillates (moving back and forth)
2. The oscillation causes the movement in surrounding air molecules
3. As the air molecules oscillate, the energy transfers to the surrounding air molecules
The periods of compression and rarefaction lead to energy transfer.
Sound travels at different speeds, depending on the medium. Even though sound travels very fast, it is still possible to measure the speed of sound over a given distance, which is measured in metres per second (m/s).
As sound travels through a medium, it travels faster in mediums with particles that are closer together. As you can see in the list above, sound travels fastest in solids, then liquids and then slowest in gases. This is because the particles of solids are closest together, then liquids and then furthest apart in gases.
When sound travels in a solid, the particles are very close together. So as they collide, they can transfer energy much quicker than other mediums.
Sound in Space
As sound waves travel through the vibrations of particles, there is no sound in space, as there are no particles in space.