Here's why:
* Compressional Waves: These waves transmit energy by compressing and expanding the medium they travel through. Think of a slinky: when you push one end, the compression travels down the slinky, causing the coils to bunch up and spread out.
* Parallel Vibration: As the compression travels through the medium, the particles in the medium move back and forth in the same direction as the wave is moving. They don't move perpendicularly like in a transverse wave (think of a wave on a string).
Examples of Compressional Waves:
* Sound waves: Sound travels through air as a compressional wave, causing the air molecules to vibrate back and forth.
* Seismic P-waves: These are the fastest type of seismic waves and travel through the Earth's interior by compressing and expanding the rock.
Let me know if you have any other questions about waves!
