Centripital ForceĀ it is a force directed towards the center of circle that keeps an object moving in circle.

The reason is because of the 1st law of motion. Remember the centripetal force? It is the force that pulls an object towards the center of the circle. And also inertia is the tendency of an object to continue what it is doing. It just means no matter how fast or big the acceleration of an object is,it would still remain at a circular path,and not go to the center. Because if it does then there would be no centripetal force applied.