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Concepts:Air Pressure, High Pressure, Low Pressure Bernoulli's Principle, Lift |
Future Quicktime Movie and photos of the demo to go here! |
Material:electric powered leaf blower works GREAT.one or two rolls of Toilet Paper a rod of dowel stick (something that will allow the paper to roll off with very little friction.)
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Procedure:Place the TP on the rod making sure that very little friction is created as it rolls off. Also make sure that the paper is positioned so it will unroll from the top and away from you. Next turn on the blower and lower the air stream so it creates a low pressure cell just above the TP. You should get at least a 15 foot streamer coming off your roll.
Background:Air, whether moving or stationary, exerts pressure. Moving are, created by blowing in this activity, has a lower pressure than stationary air (Bernoulli's Principle). The faster the are moves, the lower the pressure it exerts. So in this activity, the difference in air pressure causes the toilet paper to lift and to be carried aloft.
Application:The fact that air planes fly is an application of Bernoulli's Principle. The wings of the airplane are shaped to have a curvature. The top surface has a larger curvature than the bottom surface. As a result, the air moving over the top of the wing has to travel further than the air flowing under the bottom. Since the air most reach the other side of the wing at the same time, the top must travel faster. This creates a low pressure zone and thus lift. The wings have ajustable flaps which are used to reduce or increase the curvature of the wing and altering
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