Please help me out with is question . I am confused .?

Acceleration and velocity are vectors. They have magnitude and direction. Since this object is moving at a constant speed, its tangential acceleration is zero. For an object to move around a circle at a constant speed, the direction of its velocity must be constantly changing. This is called centripetal acceleration. The direction of the centripetal force is toward the center of the circle. This direction is always perpendicular to the direction the object is moving. I suggest that you ask the teacher to explain what he means when he says the uniform circular motion acceleration is zero. I do not agree with this statement. If you go to the following websites, you will see an example of centripetal acceleration. You will see that direction of the velocity is constantly changing.

http://www.ux1.eiu.edu/~cfadd/1150/05UCMGrav/UCM.h...

http://hyperphysics.phy-astr.gsu.edu/hbase/cf.html

Circular motion DOES involve acceleration (centripetal, as he said). Acceleration is a change in velocity. Velocity is speed in a direction. If the direction is changing, then the velocity is changing, therefore there is acceleration. Perhaps he said in uniform motion (not circular) acceleration is zero and there is constant velocity. Or maybe he just said that in uniform circular motion there was no change in speed, which is correct. If he really said uniform circular motion involves no acceleration, he was wrong.

in uniform circular motion. like that of electrons or moon, the linear speed is cinstant in magnitude, but due to continuous change of direction, it generates centripetal acceleration due to the action of centripetal force. However it will not have any angular acceleration.

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