More Bernoulli and More Unanswered Questions...
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As many of you (my non-existent readers) already know, my dad is a physics teacher. So of course physics is a regular dinner table topic of conversation in my house. Last night we were discussing fluid flow because that’s what my mom works with as a chemical engineer, and Bernoulli’s equation came up. The issue that stumped us all involves this classic scenario: when driving in a car, your hair is sucked out of the open window. The obvious explanation for this is that since the air outside the car window is traveling faster than the air enclosed in the vehicle, a pressure gradient is created (according to Bernoulli’s principle a faster fluid has lower pressure). Therefore, the hair flows from higher pressure to lower pressure, and tries to leave the car. However, our question was- what if you change the reference frame? Without getting into tons of complicated special relativity can’t we simply shift our frame of reference so that we see the air outside the vehicle as stationary and the air inside the vehicle as moving through it? If this was true then pressure inside the car would be lower. My thought was that having the air in the car enclosed somehow made it so this didn’t count as flow, but I’m unable to really think it through. Anyways, this is my physics stumper of the day.
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