Art Carlson contributed: > >I don't think the Bernoulli effect can explain an attraction in this >geometry. I would look more at the friction from the water moving in the >powerful eddy the jet sets up in the bucket. If this is correct, then a >stick held in the center of the bucket near the hose should also be pulled >in, and one held near the edge, where the water is rising will be pushed >out. The force pushing the stick up should be somewhat smaller than that >pulling it down because the friction with the wall and the greater area >available will cause the upwelling to be slower than the downdraft. If the >shape and size are similar, the stick should be pulled in with more force >than the hose, because the centrifugal force of the water in the curved >hose, which pushes it up, should still be there, cancelling some of the >force of the circulating water on the hose. I would be surprised if the hose >is actually pulled in, as opposed to be pushed out more weakly. Which way >does it move when you let go of it?
Work has got in the way of experiment today (dial on its way by airmail John!) but this evening I tried what Art suggested. RESULTS. 1. There was no appreciable change in 'semi-floatation' on a stick place near to the submerged jet or at any other point in the bucket. 2. The stick was pushed away from contact by the submerged jet but, if forced into the stream of water, there was some downward 'grabbing' effect but only when actually in the stream. 3. The hose, which has a natural curve, was held about 3 feet from the jet at which point it reared backwards out of control but if placed just below the water surface by my other hand was immediately sucked down into the water completely overcoming the spring in the hose and the reaction force which had made it rear up like a snake. I could then release the hold near the jet and it stayed under water. 4. If released altogether the hose toppled sideways, the weight of the hose pulled the jet out of the water and I got wet! Do try it for yourself! It's quite a weird sensation. Best Wishes Tony Moss
