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Author Topic: shrunken solar system  (Read 2852 times)

Offline ukmicky

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shrunken solar system
« on: 03/11/2006 02:26:35 »
If i could shrink the earth and moon until the earth reached the size of a football (i think you get what i mean) would the moon still continue to orbit the earth.


 

another_someone

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Re: shrunken solar system
« Reply #1 on: 03/11/2006 02:58:25 »
The issue is not size, it is mass.

If you reduced the mass of each, then the period of rotation would have to also reduce in order that the centrifugal force of the orbit would not exceed the reduced gravitational pull of the two bodies.  If you retained the present orbital speed, then the centrifugal force would exceed the gravitational attraction, and the two bodies would fly apart.
 

Offline neilep

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Re: shrunken solar system
« Reply #2 on: 03/11/2006 03:48:31 »
As a firm believer in empirical study I took a football and grape and found that I could not get the grape to orbit the football.

I ate the grape.


Glad I could help !
 

Offline science_guy

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Re: shrunken solar system
« Reply #3 on: 03/11/2006 08:15:35 »
your experiment is severely flawed.  did you go out into space?  a more precise example would be a watermelon and a mango, but in space, with minimal gravitational interference and orbital speed, a mango would, in fact, orbit the watermelon,

Hope it helped!
 

Offline lightarrow

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Re: shrunken solar system
« Reply #4 on: 03/11/2006 09:02:24 »
If i could shrink the earth and moon until the earth reached the size of a football (i think you get what i mean) would the moon still continue to orbit the earth.
Yes, if the masses would remain the same. However the orbit wouldn't probably be exactly the same, because, even if their distance is large, earth and moon are not point objects, so the gravitational interaction cannot be computed, with high precision, under this assumption; so, shrinking them so much would mean a difference.
 

Offline daveshorts

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Re: shrunken solar system
« Reply #5 on: 03/11/2006 09:34:05 »
The main effect that the non-pointlike nature of the earth and the moon is going to have is that it causes tides, and hence is causing a transfer of energy from the rotation of the earth to the orbit of the moon. But to a first approximation they would orbit the same.

If you didn't keep the mass constant, you could get them both to orbit, but very very very slowly. It wouldn't be enough to take a melon and mango into space, you would have to take them a long long way away from the sun or any other large body, to stop the variations in the sun's gravity being stronger than the gravity from the water melon.
 

The Naked Scientists Forum

Re: shrunken solar system
« Reply #5 on: 03/11/2006 09:34:05 »

 

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