For a particle moving in a circle,can $a_t\neq 0$ and $a_r= 0$? [duplicate]

I know for a fact that if a particle is moving in a circle such that the value of radial acceleration is non-zero and the value of tangential acceleration is zero ,then it can be classified as circular motion.But I was wondering if the opposite can be true ,i.e. $a_t\neq 0$ and $a_r= 0$ ? Would the particle be moving in a circle if this was to happen?

• It would move in a straight line
– Rol
Oct 13 '15 at 19:06
• @Rol that should be (expanded into) an answer Oct 13 '15 at 19:08
• Possible duplicate of Is centripetal acc. mandatory for circular motion? Oct 13 '15 at 19:14

To directly answer your question, assuming the particle is somehow confined to a circular motion then either the speed is 0 or the radius is infinite (i.e. a straight line), since $0 = a_r = \frac{v^2}{r}$.