1. A medium: Mechanical waves require a material medium to travel through. This medium can be solid, liquid, or gas. The particles of the medium vibrate and transfer energy to their neighbors, creating the wave.

* Examples: Sound waves travel through air, water waves travel through water, and seismic waves travel through the Earth.

2. A disturbance: A mechanical wave is created by a disturbance in the medium. This disturbance can be a vibration, a pulse, or any other form of energy transfer that causes the particles of the medium to move.

* Examples: A vibrating tuning fork creates sound waves in the air. A stone dropped in a pond creates water waves. An earthquake creates seismic waves in the Earth.

Without a medium or a disturbance, a mechanical wave cannot exist.

Here are some key points to remember:

* Mechanical waves do not transfer matter: The particles of the medium simply vibrate back and forth or up and down, transferring energy but not their position.

* Different types of waves have different speeds: The speed of a mechanical wave depends on the properties of the medium it travels through. For example, sound travels faster in solids than in liquids or gases.

* Electromagnetic waves do not require a medium: They can travel through the vacuum of space, unlike mechanical waves. Examples include light, radio waves, and X-rays.