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

  • Thread starter Thread starter skier07
  • Start date Start date
  • Tags Tags
    Change Pressure
AI Thread Summary
When traveling on a train with an open window, eardrums can "pop" due to changes in air pressure caused by the train's speed. According to Bernoulli's equation, an increase in velocity leads to a decrease in pressure, suggesting that eardrums would pop outward as the pressure outside the window drops. However, the discussion highlights that turbulence around the train may complicate this scenario, as it doesn't significantly alter atmospheric pressure beyond the immediate area. Factors such as wind direction and ear shape can also influence the sensation of popping. Overall, the question lacks clarity and could benefit from more precise definitions.
skier07
Messages
8
Reaction score
0

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

 
Physics news on Phys.org
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:
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Back
Top