I am attempted this question a few different ways and I am stuck

PROBLEM:

An object follows a circular path with a radius of 30meters. The acceleration of the object along the path is given by the equation a = 6s where a is in m/s^s and s is the distance traveled along the path in meters.

If the initial velocity is 9m/s, find the magnitude of the acceleration when it has traveled 24meters.

I thought I was doing it right.

Please help

ATTEMPT: