The acceleration is not constant, i.e. its direction changes although the magnitude is constant (III is wrong), another thing that makes III wrong is the fact that the acceleration is not directed away from the centre but towards the centre. - No work is done on a body undergoing circular motion - Note that when a body is undergoing circular motion ], its velocity is not constant, i.e. the direction changes, although the magnitude is constant. - Since the acceleration is directed towards the centre, the centripetal force is directed towards the centre.