Which statement best describes a mechanical wave's medium requirement?

• A. It requires no medium to carry energy
• B. It travels through a vacuum
• C. It requires a medium to carry energy
• D. It travels faster than light

Answer: (C)

Mechanical waves transfer energy by vibrating and pushing neighboring particles in a material. A medium is needed so these interactions can pass the motion along from one particle to the next, through solids, liquids, or gases. In a vacuum there are no particles to carry the vibration, so mechanical waves can’t propagate. That’s why the statement that a medium is required to carry energy is the best description.

The other ideas don’t fit because a mechanical wave doesn’t work without a medium, it cannot travel through a vacuum, and its speed doesn’t exceed the speed of light in vacuum—it depends on the medium and is typically much slower than light. For example, sound needs air, water, or a solid to move; in space there’s nothing to carry it.