Question

how are electromagnetic and mechanical waves different?
electromagnetic waves travel slower than mechanical waves.
mechanical waves can travel through a vacuum, but electromagnetic waves cannot.
electromagnetic waves can travel through a vacuum, but mechanical waves cannot.

Explanation:

Electromagnetic waves do not require a medium and can travel through a vacuum (like light from the sun reaching Earth). Mechanical waves (like sound waves) need a medium (solid, liquid, or gas) to propagate and thus cannot travel through a vacuum. Also, electromagnetic waves (in vacuum) travel at the speed of light (\(c = 3\times10^{8}\ m/s\)), which is much faster than most mechanical waves (e.g., speed of sound in air is about \(343\ m/s\) at \(20^{\circ}C\)).

Answer:

Electromagnetic waves can travel through a vacuum, but mechanical waves cannot.