Eardrums "Pop" Outward on a Train - Bernoulli's Equation

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Homework Help Overview

The problem involves understanding the behavior of eardrums in relation to air pressure changes while traveling on a train with an open window. It references Bernoulli's equation to explore whether eardrums "pop" outward or inward due to changes in air pressure as the train moves at high speeds.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Some participants discuss the relationship between velocity and pressure, referencing Bernoulli's principle and drawing analogies to other scenarios, such as airflow over a paper strip. Others question the relevance of Bernoulli's equation to the situation, suggesting that turbulence may play a significant role.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem. Some have offered insights into how pressure changes might affect the eardrums, while others express skepticism about the question's formulation and the applicability of Bernoulli's equation.

Contextual Notes

Participants note that factors such as wind direction and individual anatomy may influence the experience of "popping" ears, indicating that the question may lack clarity or specificity.

skier07
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Homework Statement



You are traveling on a train with your window open. As the train approaches its rather high operating speed, your ears "pop." Your eardrums respond to a decrease or increase in the air pressure by "popping" outward or inward, respectively. Do your eardrums "pop" outward or inward on the train? (Use Bernoulli's equation to back up your answer)

Homework Equations



P1 + .5(rho)(v1)^2 + (rho)gy1 = P2 + .5(rho)(v2)^2 + (rho)gy2



The Attempt at a Solution

 
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skier07 said:

Homework Statement



You are traveling on a train with your window open. As the train approaches its rather high operating speed, your ears "pop." Your eardrums respond to a decrease or increase in the air pressure by "popping" outward or inward, respectively. Do your eardrums "pop" outward or inward on the train? (Use Bernoulli's equation to back up your answer)

Homework Equations



P1 + .5(rho)(v1)^2 + (rho)gy1 = P2 + .5(rho)(v2)^2 + (rho)gy2



The Attempt at a Solution

Unfortunately, this is a poorly conceived question. The movement of the train through the stationary air causes turbulence around the train. It does not change the atmospheric pressure of the air outside the window (beyond the region of turbulence). Bernoulli's equation really has nothing to do with this question.

AM
 
An increase in velocity would correlate to a decrease in pressure. It's the same concept (for the purposes of this question) as blowing air over a paper strip to see that the air above the strip has decreased in pressure, which results in the paper strip being forced upwards.
 
So your ears would pop out then? Because the pressure outside the window is lower? If your eardrum is like the piece of paper that is.
 
I never notice such pop before in real life, perhaps the train is just too noisy for me to notice that...
IMO, the pop depends on the orientation, wind direction, and ear shape very much. If the wind is normal to the ear-hole rather then tangential, then there can be inward pop. Of course you can consider both cases anyway. I certainly would prefer the question be more definite.:smile:
 

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