Rotational Motion: A=rω, Tangential/Centripetal Acceleration

[anigeo]

we have in rotational motion a=rω,where r and ω are the radius of rotation and angular velocity respectively.What is a (tangential acceleration or centripetal acceleration)

 

[Simon Bridge]

we have in rotational motion a=rω,where r and ω are the radius of rotation and angular velocity respectively.

Surely $v=r\omega$?

The tangential acceleration would be $a=r\alpha$ where $\alpha=\frac{d\omega}{dt}$.