1. The problem statement, all variables and given/known data This isn't a homework question, but more like a theory question that my teacher and I are having trouble figuring out. We're trying to figure out why this ball, more or less, stays still in a high speed stream of air: http://laserpablo.com/videos/videofiles/Bernoulli.htm 2. Relevant equations Bernoulli's Principle, gravity, balancing vector diagrams. 3. The attempt at a solution The stream of air is going from the bottom/left to the top/right, and we had a couple theories. I think the ball is spinning clockwise, and bernoulli's is causing a lift perpendicular to the stream. The force of gravity is acting down, and the reason there isn't a net movement to the left is because the stream itself pushes the ball to the right. Therefore, the forces cancel out and the ball, more or less, stays still. However, my professor thinks the ball is actually spinning counterclockwise, and in that case Bernoulli's wouldn't explain why the ball is floating in midair; it would actually cause the ball to be pushed downward, correct? Is there someting we're missing here? What're your thoughts?