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Question about calculating the energy in a system

Question about calculating the energy in a system - Physics Forum

Question about calculating the energy in a system - Physics Forum. Discuss and ask physics questions, kinematics and other physics problems.


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  #1  
Old 10-10-2008, 11:36 PM
Doug Wedel
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Default Question about calculating the energy in a system



Suppose you have a tunnel 10m in diameter and a 200 km wind constantly
blowing through it. How would you calculate the energy of the system? What
units would the result be in?


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Old 10-11-2008, 12:31 AM
N:dlzc D:aol T:com \(dlzc\)
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Default Question about calculating the energy in a system

Dear Doug Wedel:

"Doug Wedel" <[Only registered users see links. ]> wrote in message
news:[Only registered users see links. ]...

Let's assume you wanted the kinetic energy, and there was no sort
of temperature change you were interested in too:

KE = 1/2 * m * v^2

KE = 0.5 ( volume_of_tunnel * density ) * velocity^2

Get volume in m^3, density is usually something like 1.295 kg/m^3
at STP, and once you tell me what "200 km" is, I might be able to
help with getting a velocity in meter / sec. Note that you could
end up with units of energy per meter of tunnel length, if you
want...


Energy is units of joules typically. Could do something like
foot pounds if you were of a mind to.

David A. Smith


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  #3  
Old 10-11-2008, 11:09 AM
Doug Wedel
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Default Question about calculating the energy in a system


"N:dlzc D:aol T:com (dlzc)" <[Only registered users see links. ]> wrote in message
news:etSHk.26$[Only registered users see links. ]...

Thanks for the answer. The speed should be 200 km/hr. Sorry.
But I think I can now work out the problem!


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