Need help making a 2D object rotate, starting from stop and accelerating.

Hello,

I am looking for help with what I think should be a simple question. I have a circular object that I want to make rotate. I would like to to start from a stop and gradually start to rotate faster and faster. The final rotation speed does not matter. I know how to make the object spin in place at a constant speed, but not from a stop with constant acceleration. Any help would be great. Thanks!