Spinning Water

If you spin a tank of water at a constant speed, it takes on a curved, parabolic shape–a demonstration often called Newton’s bucket. Here, a team from UCLA shows how it’s done, both in terms of the equipment needed and a concise explanation of the physics. In the rotating experiment, water is subjected to both gravity (which acts in a constant magnitude across the tank) and centrifugal force (which is stronger further from the axis of rotation). The shape that balances these forces is a paraboloid, which is why the water takes on that shape. (Video and image credit: UCLA SpinLab)