Final answer:
Mechanical waves require a medium to transfer energy and do not travel through a vacuum. Sound waves, a type of mechanical wave, need a medium like air to propagate, unlike light waves, which are electromagnetic and can travel through a vacuum.
Step-by-step explanation:
A mechanical wave transfers energy through a medium without permanently transferring mass from one location to another. For its propagation, a mechanical wave does require a medium, which can be a solid, liquid, or gas. The medium's material properties, such as elasticity and inertia, significantly affect the speed of the wave. Mechanical waves could be water waves, sound waves, or seismic waves. For example, the medium for water waves is water, while sound waves typically propagate through air, although they can also travel through solids and liquids.
And important clarification is that not all waves require a medium to travel: electromagnetic waves such as light can propagate through a vacuum. They do not need a physical substance to carry their energy from one location to another. However, mechanical waves differ because they involve the oscillation of particles in a medium, such as air molecules vibrating back and forth when sound waves pass through.
In summary, when a mechanical wave encounters the end of its medium and meets a vacuum, it cannot continue to propagate and instead reflects backward. In contrast, an electromagnetic wave will continue on its path in a vacuum, as it does not need a medium to continue its journey.