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Physics Quiz Question



 
 
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  #1  
Old August 6th 07, 06:05 PM posted to rec.aviation.piloting
Dallas
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Posts: 541
Default Physics Quiz Question

Brought over from RAS:


Assuming that all other variables remain constant:

An increase in temperature will result in a higher atmospheric pressure - a
higher temperature speeds up the movement of the air molecules, thereby
raising the pressure they exert on the surrounding atmosphere.

A) True
B) False

--
Dallas
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  #4  
Old August 6th 07, 08:17 PM posted to rec.aviation.piloting
Dallas
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Posts: 541
Default Physics Quiz Question

On Mon, 06 Aug 2007 14:34:07 -0400, alexy wrote:

I think you are right, but is it a trick question?


It's not supposed to be a tricky question. I posted it because everyone
seems to have a different answer for it. It's a tiny bit like the old
"airplane on a treadmill" debate.

--
Dallas
  #5  
Old August 6th 07, 09:39 PM posted to rec.aviation.piloting
Doug Semler
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Posts: 175
Default Physics Quiz Question

On Aug 6, 1:05 pm, Dallas wrote:
Brought over from RAS:

Assuming that all other variables remain constant:

An increase in temperature will result in a higher atmospheric pressure - a
higher temperature speeds up the movement of the air molecules, thereby
raising the pressure they exert on the surrounding atmosphere.

A) True
B) False


Well, the answer is false but it is a rather bogus problem, mainly
because the atmosphere is not fully contained; in other words, the
volume CAN change. The way this is worded, the fluid (atmospheric gas)
is also being used as the container. Pressure is a measurement of
normal (perpendicular) force against a surface, you can't have a
pressure without a surface against which an equal and opposite
pressure can be exerted. Since the atmosphere can expand (because it
is not closed), it doesn't have anything to exert pressure against
EXCEPT for the earth's surface.

But I invite you to think about: Of what is a temperature a
measurement, how does force relate to potential energy and mass, how
pressure relates to force and mass, how potential and kinetic energy
is related, how kinetic energy is related to velocity, what the laws
of conservation of energy entail, and what "atmospheric pressure" is).

Hint: "atmospheric pressure" is a measurement of the pressure of the
air due to the acceleration of gravity on the mass of column of air
directly above it, not as a measure of pressure against the
"surrounding" atmosphere.

  #6  
Old August 6th 07, 11:00 PM posted to rec.aviation.piloting
Capt. Geoffrey Thorpe
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Posts: 790
Default Physics Quiz Question

"Dallas" wrote in message
...
Brought over from RAS:


Assuming that all other variables remain constant:

An increase in temperature will result in a higher atmospheric pressure -
a
higher temperature speeds up the movement of the air molecules, thereby
raising the pressure they exert on the surrounding atmosphere.

A) True
B) False


False and/or True.

The air can expand. If it expands vertically, the pressure is unchanged. If
it expands horizantally, the pressure goes down. If the air is constrained,
the pressure goes up.

Depends on what you mean by "all other variables remain constant"

PV = nRT

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.


  #7  
Old August 7th 07, 02:37 AM posted to rec.aviation.piloting
Tina
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Posts: 500
Default Physics Quiz Question

the variable that matters is that there's 14.7 pounds of air over
every square inch at sea level. If that's the one that stays constant,
the answer is clear.

On Aug 6, 3:00 pm, "Capt. Geoffrey Thorpe" The Sea Hawk at wow way
d0t com wrote:
"Dallas" wrote in message

...

Brought over from RAS:


Assuming that all other variables remain constant:


An increase in temperature will result in a higher atmospheric pressure -
a
higher temperature speeds up the movement of the air molecules, thereby
raising the pressure they exert on the surrounding atmosphere.


A) True
B) False


False and/or True.

The air can expand. If it expands vertically, the pressure is unchanged. If
it expands horizantally, the pressure goes down. If the air is constrained,
the pressure goes up.

Depends on what you mean by "all other variables remain constant"

PV = nRT

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.



  #8  
Old August 7th 07, 12:16 PM posted to rec.aviation.piloting
terry
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Posts: 215
Default Physics Quiz Question

On Aug 7, 3:05 am, Dallas wrote:
Brought over from RAS:

Assuming that all other variables remain constant:

An increase in temperature will result in a higher atmospheric pressure - a
higher temperature speeds up the movement of the air molecules, thereby
raising the pressure they exert on the surrounding atmosphere.

A) True
B) False

--

The answer is true, but the usefulness of the question is doubtfall
because all things dont remain constant. In practice , at least where
I live, the temperature can change quite radily during the day with
virtually no change in pressure. But then when you talk about
synoptic charts, high pressure is associated with higher temperatures,
and vice versa for low pressure systems.
terry

  #9  
Old August 7th 07, 03:40 PM posted to rec.aviation.piloting
Doug Semler
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Posts: 175
Default Physics Quiz Question

On Aug 6, 9:37 pm, Tina wrote:
the variable that matters is that there's 14.7 pounds of air over
every square inch at sea level. If that's the one that stays constant,
the answer is clear.


Well...not to quibble, but 14.7 (ok, 14.694) psi is the MEAN sea level
pressure. There are localized variations in pressure caused by
density differences over those areas. (which is why GENERALLY
speaking, areas of lower pressure indicate "rain" systems; the lighter
air indicates a higher moisture content).

Although, in large enough volumes the differences are close enough to
zero that they do not significantly affect calculations since

lim (m/V) = 0
V-inf

  #10  
Old August 7th 07, 06:19 PM posted to rec.aviation.piloting
Dallas
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Posts: 541
Default Physics Quiz Question

On Mon, 6 Aug 2007 12:05:17 -0500, Dallas wrote:

An increase in temperature will result in a higher atmospheric pressure - a
higher temperature speeds up the movement of the air molecules, thereby
raising the pressure they exert on the surrounding atmosphere.
A) True B) False


The origin of the question comes from the current edition of the Jeppesen
Private Pilot manual.

Here's the exact text:
http://img.photobucket.com/albums/v1...allas/Jep1.jpg

Which would seem to imply that the answer is true.

If you're wondering if it's out of context, here's all the text on the
page:

http://img.photobucket.com/albums/v1...allas/Jep2.jpg


--
Dallas
 




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