What type of wave is a sound wave?

Sound waves are classified as longitudinal waves because they travel through a medium (such as air, water, or solid materials) by compressing and rarefying the particles of that medium. In a longitudinal wave, the oscillations of the particles occur in the same direction as the wave travels, resulting in areas of compression (where particles are close together) and rarefaction (where particles are spread apart).

This is different from transverse waves, where the particle displacement is perpendicular to the direction of wave propagation, as seen in waves on a string or electromagnetic waves. Electromagnetic waves, which include visible light, radio waves, and X-rays, do not require a medium to propagate and can travel through a vacuum. Circular waves refer to waves that spread out in a circular pattern from a point source, but this description does not specifically apply to the nature of sound waves.

Therefore, the correct classification of sound waves as longitudinal stems from their behavior in transmitting energy through a medium by the movement of particles in the direction of the wave's travel.