The particles in a material move back and forth along the direction of wave motion in a longitudinal wave.

Here's a breakdown:

* Longitudinal Waves: In a longitudinal wave, the particles of the medium vibrate parallel to the direction the wave travels. Imagine a slinky: when you push one end, the coils compress and then stretch out as the compression travels down the slinky.

* Examples: Sound waves are a great example of longitudinal waves. The particles in the air compress and expand as the sound wave travels.

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