Here's why:

* Particle Density: Solids have the highest density of particles compared to liquids and gases. This means particles are closer together, allowing vibrations to be transferred more efficiently.

* Intermolecular Forces: Solids have strong intermolecular forces holding the particles tightly together. These forces help transmit vibrations quickly.

In contrast:

* Liquids: Particles in liquids are less tightly packed and have weaker intermolecular forces, so vibrations travel slower.

* Gases: Particles in gases are far apart with weak intermolecular forces. This makes vibration transmission very slow.

Important Note: The speed of a mechanical wave also depends on the properties of the medium, such as its elasticity and density.