How can I calculate the centripetal acceleration in nonuniform circular motion?

[Gear300]

I've come back once more with a question.

-A hawk is flying along a horizontal arc (the path it takes is similar to a semicircle), in which the radius is 12.0m and the tangential acceleration is 1.20 m/s^2.
All that has to be found is the net acceleration.

-I know that the centripetal acceleration is constant (otherwise it most likely wouldn't be a circle) and the tangential acceleration is constant. So the the centripetal acceleration and tangential acceleration must be components of the net acceleration. How would I solve for the centripetal acceleration?

 

[Shooting Star]

You are wrong. The centripetal accn is v^2/r, and if r is const but v is not, it's not const.

Do you know the expression for tangential and normal accns? Use the formula:

a = (dv/dt)T + (v^2/r)N, where T is the unit tangent vector and N is the unit normal vector.

 

[Gear300]

I see. So v^2/r applies even to nonuniform circular motion...

 

[Shooting Star]

From the given value of dv/dt, find v. You may have to make some assumptions.