Question

which is an example of the transfer of energy by a longitudinal wave?
a) a large ocean wave knocks a person down.
b) a guitar string vibrates after being plucked.
c) a door slams, and someone in the next room hears the sound.
d) seismic waves cause the ground to move up and down during an earthquake.

Explanation:

• Option A: Ocean waves are transverse waves. In transverse waves, the particle motion is perpendicular to the wave propagation direction.
• Option B: A vibrating guitar string is a transverse wave on the string itself (the particles of the string move perpendicular to the length of the string as it vibrates).
• Option C: Sound is a longitudinal wave. In a longitudinal wave, particle motion is parallel to the wave propagation direction. When a door slams, it creates a disturbance in the air. The air molecules vibrate back - and - forth (parallel to the direction the sound wave travels) to transfer energy, allowing someone in the next room to hear the sound.
• Option D: Seismic waves (specifically S - waves, which cause up - and - down ground motion during an earthquake) are transverse waves.

Answer:

C. A door slams, and someone in the next room hears the sound.