Smooth acceleration/deceleration on Circle

I am working on a game where the player controls the movement of an object around a circle. When the object starts moving, I want it to accelerate smoothly to the maximum speed, and when the object stops moving, i want it to decelerate to a stop.

I have the actual movement down fine, but the math for the acceleration/deceleration is escaping me. I know I should be able to use lerp, but my math skills are lacking.

Here is an example capx:

https://dl.dropbox.com/u/38038537/examples/SmoothMove_example.capx

Press left and right arrow to move the ship.

Any help would be appreciated.

Thanks!

radialAcceleration.capx

Brilliant! Thanks Yann!