* Constant Speed: This means the magnitude of the velocity vector remains the same.
* Acceleration Perpendicular to Velocity: This means the acceleration is always changing the *direction* of the velocity, but not its magnitude.
Imagine a ball tied to a string, swinging in a circle. The string provides a constant inward force (centripetal force), which causes the ball to accelerate towards the center of the circle. This acceleration is always perpendicular to the ball's velocity (which is tangent to the circle).
Key Concepts:
* Centripetal Acceleration: The acceleration directed towards the center of the circular path. Its magnitude is given by a = v²/r, where v is the speed and r is the radius of the circle.
* Uniform Circular Motion: Motion in a circle at a constant speed.
In summary: When a particle moves with constant speed and its acceleration is always perpendicular to its velocity, it is undergoing uniform circular motion.
