Bernoulli's Principle
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Minority and Female Physics Heros Bernoulli’s Principle Wind Farms: How do the blades turn? Resources/Materials: Three sheets of paper, tape, scissors, a ruler, a drinking straw, a ping pong ball, 6 paper clips Observe and Find a Pattern: For your first activity, take a strip of paper [about 2 inches wide] and put it on your chin close to your lips [hold it with your thumb]. Blow straight out over the paper. Describe what you see. ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... Attach a paper clip to the paper and blow down on the paper again. What happens this time? How many paperclips can you attach to the paper? ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... Now take two sheets of paper and hold them parallel to each other straight in front of you. Keep the papers about five centimeters apart. Now blow between them. What happens to the papers? ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... Are there any noticeable patterns based on these observations, if so, what is (are) the patterns? ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... Testing Experiment: Take a bendable straw and a ping pong ball. Do not do the experiment just yet. You are going to bend the end of the straw so that it is at a ninety degree angle. You will blow into the straw and then place the ping pong ball about one or two inches above the end of the straw. Predict, based on your answer to the last question, what do you expect to happen. ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... Physics of Flight 2 If you have shortness of breath or have anything asthma related, please have a lab partner blow through the straw. Perform the experiment and describe what happens. ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... Does this outcome match your prediction? If not then modify your pattern answers. ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... What if you move the straw at a slight angle, what should happen to the ping pong ball? ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... Perform the experiment and describe what happens. ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... Does this outcome match your prediction? If not then modify your pattern answers. ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... This physics phenomenon is called Bernoulli’s principle and is part of the reason of what helps make an airplane fly and turn the turbine blades on windmills. Bernoulli's principle states that when the velocity of any fluid increases, its pressure decreases. Remember that air is a collection of gases and gases are a fluid. Thus, if you can make the air on one side of an object move faster, this will lower the pressure on that side. Faster moving air – less pressure Slower moving air – more pressure Bernoulli's principle plays a role in airplane wings. In motion, air hits the leading edge (front edge) of the wing. Some of the air moves under the wing, and some of it goes over the top. The air moving over the top of the curved wing must travel farther to reach the back of the wing; consequently it must travel faster than the air moving under the wing. Therefore the air pressure on the top of the wing is less than that on the bottom of the wing. This creates a lift in the wings, moving the plane upwards. Note that this is one theory in how airplanes fly. Physics of Flight 3 Explain the picture below in terms of Bernoulli’s principle: ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... (picture was taken from http://www.crh.noaa.gov/grb/events/062304.php) Do some research on windmill blades and report it here. Be sure to investigate at least the following: how Bernoulli’s principle is related to the shape of the blade and how and why the blades are positioned with respect to the wind. ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... Extension: Where else do you experience Bernoulli’s Principle in everyday life? ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... ....................................................................................................................................................................................................... .......................................................................................................................................................................................................
