In physics, it is incorrect to say that there is no acceleration when an object moves in a uniform circle. In fact, an object moving in a circle at a constant speed experiences acceleration continuously, even though its speed remains constant.
The reason for this is that acceleration is not solely defined as a change in speed but also includes changes in direction. In circular motion, the object is constantly changing direction, which means it is accelerating even if its speed remains constant.
The acceleration in circular motion is known as centripetal acceleration and is directed toward the center of the circle. It is given by the formula:
a = (v^2) / r
Where: a is the centripetal acceleration, v is the velocity (speed) of the object, and r is the radius of the circle.
So, although the speed of an object moving in a uniform circle does not change, its velocity is constantly changing because the direction of its velocity vector is changing. This change in velocity results in a non-zero acceleration toward the center of the circle, providing the necessary force to keep the object in its circular path.
It's important to note that while the object experiences centripetal acceleration, it does not experience tangential acceleration (acceleration in the direction of motion) if its speed remains constant.