I have a very simple test question about acceleration. A ball is moving at a constant speed inside of a hollow sphere. The question is whether or not the ball is accelerating. I said that it was not accelerating because the ball is always moving forward, even though it is traveling in a circular path. My teacher said that it was accelerating but the only explanation that I was given was that the ball is moving in a circle. This is a very simple question, but it is bothering the heck out of me.