Uniform circular motion

Uniform circular motion can be said as the motion of an object in a circle at a constant speed. As an object moves in a circle, it is constantly changing its direction. At all time, the object is moving tangent to the circle. Since the object is going in a circle, it's velocity keeps changing and this makes the object accelerate. Even though it's accelerating the speed in a uniform circular motion is constant because the acceleration is due to change in direction.

An object would continue in a straight line, never differing from its direction. Since the centripetal force is present in the circular motion, this force will be perpendicular to the velocity vector; due to this the object is always changing its direction and undergoing an inward acceleration. 

Centripetal force does not exist by its self, but is given by the action of other forces. For example, a fairground ride consists of a number of chairs suspended from wires that swing out as the centre rotates faster and faster. Imagine the ride going around in a circle. The centripetal force is the result of tension within the wire attached to the chairs where the person sits.

Also the fairground ride doesn't have uniform circular motion because it’s speed isn’t constant, it starts of slow and increases as it goes around many times.