Final answer:
Mechanical waves require a medium to travel, such as sound waves needing air, water, or rock, while electromagnetic waves like light do not require a medium and can travel through a vacuum.
Step-by-step explanation:
The type of wave that requires a medium in which to travel is a mechanical wave. Unlike electromagnetic waves, mechanical waves such as sound waves, water waves, and seismic waves cannot travel through a vacuum; they need a medium like air, water, or rock. Mechanical waves are governed by Newton's laws, and they involve the transfer of energy and momentum through the vibrations of particles within the medium. The medium's properties, such as elasticity and density, significantly impact wave speed and behavior.
An example of mechanical waves is sound waves, where air usually acts as the medium. However, electromagnetic waves like light and radio waves do not require a medium and can travel through the vacuum of space at the speed of light (c = 2.99792458 × 108 m/s).