What is vibration?

Explanation

**Step-by-Step Text Solution:**

1. **Definition of Vibration**: Vibration can be defined as the periodic, rapid motion of particles in an elastic body or medium from their mean equilibrium position when that position is disturbed.

2. **Understanding Mean Position**: The mean position refers to the resting or equilibrium position of a particle. It is the position where the particle would naturally be if it were not disturbed.

3. **To and Fro Motion**: When a particle vibrates, it moves to one side of the mean position and then back to the mean position, and then to the opposite side, repeating this motion. This is known as to and fro motion.

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