A car travels at a constant speed around a circular track whose radius is 2.6 km. The car goes once around the track in 330 s. What is the magnitude of the centripetal acceleration of the car?

and i get 9.4E-4 m/s^2

and that seems to be the wrong answer.

first i used: (2 * pi * r) / T

and then

i used: a = v^2 / 2 for centripetal acceleration

please help me with this one.