What is the fractional decrease in pressure when a barometer is raised 35 m to the top of a building? (Assume that the density of air is constant over that distance.)

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- Jul 25th 2006, 04:32 PM #1

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- Jul 25th 2006, 07:55 PM #2

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Originally Posted by**babygirl**

If this was my problem I would look up in my text book or do a google search

for the altitude dependence of air pressure (giving priority to my text book

or what I have been told by my teacher).

There I might find air pressure drops by about 1 part in 1000 for every 8m

increase in altitude, for altitudes of less than a few hundred metres.

Alternatively you might find that the half height of the atmosphere for air

pressure is ~5000m

We really need to know what you are supposed to know about atmosheric

pressure before we can help you with this question.

RonL

RonL

- Jul 26th 2006, 05:01 AM #3Originally Posted by
**babygirl**

$\displaystyle P = P_0 + \rho g \Delta h$

so the fractional decrease would be

$\displaystyle \frac{\rho g \Delta h}{P}$.

(I'm presuming P is at sea level.)

-Dan