Here's why:
* Velocity is a vector: Velocity has both magnitude (speed) and direction. In circular motion, the speed might be constant, but the direction of the velocity is constantly changing.
* Acceleration is a change in velocity: Any change in velocity, whether in magnitude or direction, means there is acceleration.
* Towards the center: The change in velocity is always directed towards the center of the circle. This is because the object is constantly being pulled inwards, preventing it from flying off in a straight line (which is what it would do if there were no force acting on it).
Think of swinging a ball on a string. The string is constantly pulling the ball towards your hand (the center of the circle). This inward pull is what causes the centripetal acceleration and keeps the ball moving in a circle.
