Here's why:

* Simple Harmonic Motion: Most vibrations we talk about are modeled by simple harmonic motion (SHM). In SHM, the object oscillates back and forth around a central equilibrium point.

* Extreme Positions: The extreme ends of vibration are the points furthest from the equilibrium position.

* Velocity at Turning Points: At these extreme points, the object momentarily comes to a stop before changing direction. This means the velocity is zero at these points.

Think of a pendulum:

* At the highest points of its swing, the pendulum momentarily stops before swinging back down. Its velocity at those extreme points is zero.

Key Takeaway: In SHM, the maximum velocity is at the equilibrium point, and the velocity is zero at the extreme ends of the oscillation.