An object in uniform circular motion moves at a constant speed around a circle with a fixed radius. Why is the object said to be accelerating though it has a constant speed?

The object in uniform circular motion is said to be accelerating because acceleration is not only related to changes in speed but also changes in direction. Even if the object is moving at a constant speed, its direction is continuously changing as it goes around the circle.

To understand why this is considered acceleration, we need to remember that acceleration is a vector quantity. It has both magnitude and direction. In the case of circular motion, the direction of acceleration is always toward the center of the circle. This acceleration is called centripetal acceleration.

Centripetal acceleration keeps an object moving in a circular path by continuously changing its direction inward toward the center of the circle. This inward acceleration is necessary to counterbalance the outward force, known as centrifugal force, which would cause the object to move in a straight line tangent to the circle.

In conclusion, even though the object's speed remains constant, it is said to be accelerating because its direction is changing, and there is a continuous inward acceleration acting on it to maintain its circular path.

An acceleration is defined as the change of velocity per unit time. Since the velocity changes with time even the speed is constant, so there is an acceleration.