Maximum Pressure Applied to Hand While Racing at 220mph

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Discussion Overview

The discussion revolves around estimating the maximum pressure applied to a hand when it is extended out of an open car window while traveling at high speeds, specifically comparing 70 mph and 220 mph. The context includes theoretical applications of fluid dynamics, particularly the Bernoulli equation, and the challenges faced in solving the problem due to multiple unknowns.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses difficulty in applying the Bernoulli equation to estimate the pressure, noting that the textbook problems seem simpler and that there are too many unknowns in their worksheet.
  • Another participant suggests that Bernoulli's principle can be applied along a streamline and encourages considering a streamline from infinity to the hand.
  • A different participant mentions that the solution involves stagnation pressure and advises writing the Bernoulli equation between a far field point and the point on the hand, emphasizing the need for air density at 20°C.

Areas of Agreement / Disagreement

Participants generally agree that the Bernoulli equation is relevant to the problem, but there is no consensus on how to effectively apply it due to the complexities involved and the presence of multiple unknowns.

Contextual Notes

Participants highlight the need for specific values such as air density and express uncertainty regarding the application of the Bernoulli equation in this context, indicating potential limitations in the provided information.

*titanium*
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Estimate the maximum pressure that would be applied to your hand if oyu were told it out of an open car window while the car travles at 70mph through still ait at 20 degrees c what would be the maximum pressure applied to your hand if the car where a formula one race car traveling at 220mph

I think I am suposed ot use the Bernoulli equation but it doesn't work, iv looked at questions in the textbook and they are much simpler, on the work sheet iv got I always seem to have too many unknowns.
 
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I HAVE A THERMODYNAMICS QUESTION THAT I NEED ASSISTANCE WITH.

NITROGEN FLOWS THROUGH AN INSULATED PIPE AT A STEADY STATE THROUGH A PARTIALLY OPENED VALVE. THE INSIDE DIAMETER IS 1.5 inch> JUST BEFOR THE VALVE THE UPSTREAM PRESSURE INSIDE THE PIPE WAS Pup =120psia AT A TEMPERATURE OF 12O degrees fahreheit. THE GAS VELOCITY WAS MEASURED TO BE 20 feet per second.
THE PRESSURE ON THE DOWN STREAM SIDE OF THE VALVE WAS MEASURED TO BE P down =20 psia. HOW WOULD YOU OBTSIN THE TEMPERATURE JUST DOWN STREAM OF THE VALVE.
 
Titanium: You need to show some sort of effort on your part.

Gizzy: Do not hijack threads with a different topic. If you need assistance, create your own thread and follow the forum guidelines by showing how you have attempted to do this problem.
 
Last edited:
*titanium* said:
Estimate the maximum pressure that would be applied to your hand if oyu were told it out of an open car window while the car travles at 70mph through still ait at 20 degrees c what would be the maximum pressure applied to your hand if the car where a formula one race car traveling at 220mph

Bernoulli would be correct. Think about it, Bernoulli can be applied along a certain streamline. Consider a streamline from infinity...
 
It s stagnation pressure

What you need to do is to write Bernoulli equation between a far field point and a point on your hand.You will simply get the solution.It s not so complicated.What you need to know extra is the air density at 20°C.You can glance through appendixes of thermodynamics or fluid mechanics textbooks. good luck!
 

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