Weight/Satellite Above Earth's Surface


by sweetpete28
Tags: earth, surface, weight or satellite
sweetpete28
sweetpete28 is offline
#1
Apr14-12, 09:21 PM
P: 80
Satellite of mass 457 kg orbits at 8.44 x 10^6 m above earth.

What is weight of 62.3kg man in satellite?

Acceleration due to gravity created by Earth at distance of satellite = GMe / r^2 = 1.82m/s^2 ...this is RIGHT.

So to get weight of astronaut I multiplied 1.82 by 62.3 = 113N...but this is WRONG...can someone please advise why?
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gneill
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#2
Apr14-12, 09:48 PM
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Quote Quote by sweetpete28 View Post
Satellite of mass 457 kg orbits at 8.44 x 10^6 m above earth.

What is weight of 62.3kg man in satellite?

Acceleration due to gravity created by Earth at distance of satellite = GMe / r^2 = 1.82m/s^2 ...this is RIGHT.

So to get weight of astronaut I multiplied 1.82 by 62.3 = 113N...but this is WRONG...can someone please advise why?
No doubt that would be his weight if he were held stationary above the Earth at the given altitude, with no angular motion. But he is in orbit, and thus free-fall. If he were to place a spring scale between himself and the downward facing "floor" of the satellite, what do you suppose it would read?
PeterO
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#3
Apr15-12, 07:22 AM
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P: 2,316
Quote Quote by sweetpete28 View Post
Satellite of mass 457 kg orbits at 8.44 x 10^6 m above earth.

What is weight of 62.3kg man in satellite?

Acceleration due to gravity created by Earth at distance of satellite = GMe / r^2 = 1.82m/s^2 ...this is RIGHT.

So to get weight of astronaut I multiplied 1.82 by 62.3 = 113N...but this is WRONG...can someone please advise why?
Just checking that you considered the difference between the distance above the earth [presumably the surface] and the Radius of the orbit - the distance to the centre of the Warth.

You are then faced with whether you are after the actual weight, or the apparent weight.


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