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nHowndid studying the speed of blood flow and blood pressure help usndesign airplanes?
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nDutch-Swissnmathematician and scientist Daniel Bernoulli (born on this date inn1700) observed and tested the flow of fluids, that is, liquids andngases. He tried to understand how the speed of blood flow in veinsnand arteries related to the pressure it exerts. To find out, henpunched holes in pipes and inserted vertical straws, and then henmeasured the height to which the fluid rose up the straw. Here’s whatnhe found:
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nThenquicker the motion of fluid in the pipe, the less the pressurenexerted, and the lower the level of fluid in the vertical straw. Whennfluid moves at lower speeds, it exerts more pressure and pushes upninto the straw to a higher level. Bernoulli was able to devisenmathematical equations to match his experimental findings.
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nHerenis an animation you can manipulate to see the difference innspeed-of-motion (velocity) and pressure, depending on the shape of anpipe. Be sure to “grab” and “drag” the little yellow boxes tonchange the shape—then check out the graphs below that show thenrelation of the speed to the pressure. Make really exaggerated shapesnwith a really narrow mid-portion, for example, and one very wide end,nto see the results most clearly.
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nApparently,nfor more than a century, based on Bernoulli’s findings, doctorsnmeasured blood pressure by sticking point-ended glass tubes directlyninto people’s arteries. Eeek! I feel glad that a less invasive andnpainfully method was eventually invented!
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nLaternon, airplane wings were designed to take advantage of Bernoulli’snprinciple—with the air moving more quickly over the top of thenwing, creating less pressure—and therefore providing lift as thengreater pressure under the wing pushes the wing up.
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nBernoulli’snfluid mechanics have been used in many other ways, of course; also,nBernoulli made other contributions to mathematics, statistics, andnscience. So hooray for Bernoulli!
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nAlsonon this date:
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nXerox inventor Chester Carlson’s birthday
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nCulture Day in Slovenia
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