Reaction to O rolling around

I think that my O works because of the motion implied by the landscape behind it. I liked looking at everyone's works and it did not escape me that a great deal of students have a much better grasp of flash than I do. But I still am loyal to my O.

The o is seen rolling up a hill and then down it, into a wall. The speed lines make the circle look like it is moving along with the fact the hill rolls by. I think that it is easy to think the o is rolling because of how it is drawn slightly differently in each frame. I wanted to have the circle tilt sideways like a tire on a vehicle in a cartoon.