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? Earth's Gravitational Field Effect on space shuttles

  • Thread starter samaank
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15
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???? Earth's Gravitational Field Effect on space shuttles

Hi, i have a physics question in my physics portfolio, it goes as follows

Critically assess the following statement: ‘Astronauts in a space capsule orbiting the earth at a height of 900km experience weightlessness: hence the gravitational field due to the earth must be zero at that altitude'. Include calculations in your answer.

Can someone please help ?
 

Answers and Replies

HallsofIvy
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Do you know the formula for the strength of earth's gravitational field?

[tex]F= \frac{GM}{r^2}[/tex]

Where G is the "universal gravitational constant", M is the mass of the earth, and r is the distance from the center of the earth (radius of the earth plus altitude). For what value of r is that 0?

Whe DO astronauts experience weightlessness? (What weight would you feel if you jumped off the edge of the Grand Canyon?)
 
15
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thank you very much, your post made something click in my mind, i got it now. thanks
 
15
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HallsofIvy said:
Do you know the formula for the strength of earth's gravitational field?

[tex]F= \frac{GM}{r^2}[/tex]

Where G is the "universal gravitational constant", M is the mass of the earth, and r is the distance from the center of the earth (radius of the earth plus altitude). For what value of r is that 0?

Whe DO astronauts experience weightlessness? (What weight would you feel if you jumped off the edge of the Grand Canyon?)
ok i thought i had it but i didnt, could u please prove that theory mathematically, i tried inputting the numbers but ended up with 610.24234......
 
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Astronauts donot feel weightless because of earth's gravitational field =0 , infact the gravitational field due to earth is not zero by any means at a height of 900 km. Astronauts would feel weightless if their space-shuttles accelerated in such a way that it counterbalanced the earth's attraction.Astronauts could feelw eightless if they were under freefall in space , like in case of satellites orbiting earth, in this case earth's gravitational field helps in motion of satellite and is not zero.Earth's Gravitational field will be zero when r---> infinity.

BJ
 
15
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how would i prove that mathematically ?
 
HallsofIvy
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I'll try one more time- the question asked whether the force of gravity was 0.

[tex]F= \frac{GMm}{r^2}[/tex]

For what value of r is that 0?
 

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