A small science experiment

| Comments (2) | Misc
I noticed the other day that if I'm driving my car on the freeway and close the sunroof my ears pop. After a bit of thinking, I concluded that what was going on was the Bernoulli effect: the air flowing over the sunroof lowers the pressure of the interior of the car. Then when you close it you get a sudden pressure change back to ambient pressure.

Initial experiments confirm this: my Polar 625SX has a built-in barometric altimeter. I repeatedly opened and closed the sunroof and watched the altimeter and readings seemed to consistently differ by about 75 feet. Obviously, there's some uncertainty here because the road isn't totally flat; if you wanted to be really sure you'd go over the same sections of the road again and again with the sunroof open and closed and measure the difference. Still, since I'm not exactly publishing this in Nature, it seems good enough for now.


I reached the same conclusion once, except that for "pop" read "started ringing, and rang for about four days".

Hmm - 75 feet should not be enough to make your ears pop

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