Here's why:
* Equilibrium means a state of balance where there is no net force acting on the particles.
* In a medium, like air or water, particles are constantly moving and interacting.
* When there's no disturbance, these interactions lead to a state where the particles settle into a specific arrangement, called their equilibrium position.
Think of it like this:
* Imagine a bunch of marbles in a bowl. They might move around a bit, but eventually, they'll settle at the bottom of the bowl. This "bottom of the bowl" represents the equilibrium position.
* Now, imagine dropping a pebble into the bowl. The marbles will move and scatter, creating a disturbance. But once the disturbance settles down, the marbles will return to their equilibrium position at the bottom of the bowl.
In the context of waves, the equilibrium position is the point where the particles would be if there were no wave traveling through the medium. The wave displaces the particles from this position, causing them to oscillate around it.
