Dear Dr. Science:

You've got to help me settle this argument I am having with my girlfriend. We were watching a football game the other night. When the quarterback threw the ball to the wide receiver, my girlfriend told me that when the ball reached the maximal height its vertical velocity was zero but its acceleration was not zero. I said she was crazy. If something does not move, how could it have any acceleration? Dr. Science, could you help us settle this argument?