Why do sound waves move faster through the ground than through the air? a. particles of matter are packed more loosely in the ground than in the air. b. particles of matter are packed more tightly in the ground than in the air. c. air doesn’t contain any particles of matter to transmit sound waves. d. the elevation of the ground is lower than the elevation of the air space.

The correct answer is

b. Particles of matter are packed more tightly in the ground than in the air.

Sound waves generally move faster in solids than liquids and gases. The reason is that sound waves are vibrations of the molecules of the medium: therefore, if the particles of the medium are closer together (as in solids), the vibrations can be transmitted faster, and the wave can travel faster. On the contrary, in gases the particles are spread apart, so the vibrations are not transmitted so easily (because there are less collisions between the particles) and the wave travels slower.

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