We know that the magnitude of tangential component of acceleration is, atangential = dv/dt (where v is speed) So clearly atan = 0 for uniform circular motion (as v is constant) But what about non-uniform circular motion? I can see atan = 0 only when v = constant. But in non uniform circular motion v is not constant. Does it mean that atan can never be zero if the particle is moving in non-uniform circular motion? (It never seems to be the case.) Would someone please explain?