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# Three Lies You Learned in School

Everyday Einstein explores 3 lies students often learn in school and the true facts behind them.

By
Lee Falin, PhD,
June 28, 2013
Episode #060

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One of the interesting things about science is how hard it is for new discoveries and ideas to trickle down to the elementary education level. I’ve always felt there were two reasons behind this.

The first is that it takes a surprisingly long amount of time for information uncovered in new research to make it into textbooks. Some branches of science change so quickly (especially biology) that many textbooks are incorrect at the time of printing.

Another reason is that many people believe they know a fact already, since they learned it in school when they were kids. So they never bother checking to see if that fact is still true. Let’s look at some common examples.

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## How Airplanes Fly

One of the most persistent falsehoods in modern education is how airplanes fly. Most people know that airplanes fly because a force, commonly called lift, is applied to the wings. But if you ask a hundred random people what causes this lift, I’m willing to bet that over half of them will tell you some version of the equal transit time theory.

This theory says that when the wing is moving through the air, the air is split in half by the wing. Since the upper surface of the wing is curved, the air has to travel a greater distance than the air underneath the wing. So in order to keep up with the air underneath the wing, the upper part of the air has to travel faster. Faster moving air results in lower pressure, and since the pressure above the wing is lower than the pressure below the wing, we get lift! Right? Wrong.

The problem with this theory is that the upper part of the air doesn’t care one bit about keeping up with the lower part of the air. Unfortunately this theory is so popular that it still exists in modern textbooks and even some pilot manuals. There are several other incorrect or partially correct explanations about why airplanes fly, but the truth is fairly complicated. For a full explanation, check out NASA’s excellent “What is Lift” website.

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