Is it travels is fastest when you travels alone?

Yes, though in many situations it is not advisable.

The answer to "What is the fastest thing that can travel?" is light. Light can travel faster than any other thing in the universe!

Things that have mass require energy to go fast. Anything that has mass requires an infinite amount of energy in order to go the speed of light. Light has no mass, so it can go the speed of light...

it depends on the kind of material medium it occurs on. and it's wavelenght.

The speed of sound in a material is governed by two properties: Inertial (the density) and Rebound (the return to position after deformation). The higher the density, the faster sound travels. The...