Mechanics/Dynamics/Motion

Water Cannon

This exhibit has two short tubes through which a constant flow of water is directed away from the center, and two longer tubes with "U" bends at the ends that directs the water towards the center. When the tubes are rotated, as seen in the photo, the water streams forms an arcs, but, you might be surprised to see, in opposite directions. The inward moving water veer forward, ahead of the tube, the outward moving water lags behind the tube. Water leaves each of the tubes traveling sideways, pushed by the moving tube. But the the outer end of the tube the close-in end of the tube. This means that the water streaming inward from the long tube is traveling sideways faster than the inner part of the tube. With an excess of sideways speed, the stream veers ahead of the tube as it moves inward.