Re: Flying High ?

Date:         03 Mar 98 03:12:48 
From: (Daniel F Boyd)
Organization: State University of New York at Buffalo/Computer Science
References:   1 2
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In article <airliners.1998.358@ohare.Chicago.COM>,
Chris Pitzel  <> wrote:
> For example, I weigh roughly 130 pounds at sea level, yet I
> would only weigh perhaps 110 pounds at 40k feet.


> There are formulas to
> determine this which can be derived from the relationship:
> 	F = G*m1*m2/r^2
> Where F is the force between the two bodies, G is the gravitational
> constant, m1 is the mass of one of the particles, m2 is the mass of the
> other particle, and r is the distance between the centres of the two
> particles.  Anyone who has taken an introductory physics course of any
> kind will have seen these formulas.

The radius of the earth is 6.378e6 meters.  Your 40,000 feet added
onto sea-level altitude is 6.390e6 meters.  So the force of gravity on
you is going to be 0.996 of what it is at sea level.  This turns your
130 pounds into 129.5 pounds.

You lose about half a pound.  Your estimate was off by a factor of 20.

(Would you care to pay 17 dollars for a candy bar?)

-- Dan