In a circular motion even if there is a constant velocity the velocity vector undergoes a change in direction. This change in direction implies that there is an acceleration in the radial direction and is equal to:
[tex]a_c=\frac{v^2}{r}[/tex]Where:
[tex]\begin{gathered} a_c=\text{ centripetal acceleration} \\ v=\text{ velocity} \\ r=\text{ radius. } \end{gathered}[/tex]