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.