# Thread: If you tied the Earth to the Moon with a giant chain...

1. ## If you tied the Earth to the Moon with a giant chain...

(Let's pretend the moon is matching the exact rotation of Earth for a minute, because otherwise the chain would just spiral around the Earth).

Could you theoretically pull them together with ease considering they are simply objects in space? Or would the entire mass/gravity thing play a role in it? Because otherwise the gravitational pull of the Earth-end of the chain would pull the moon, as the whole 'weightless object regardless of size' theory would come into play.

Also if we come back to reality and the whole rotation thing is back, when the moon rotates around the Earth and ties the chain around the Earth like a string around a ball (since the Moon rotates around the Earth ofc), would they slowly come closer together until they collide as the chain length runs out? Or would they alter each other's spin, like as if the Earth's spinning power is greater than the moons, so the moon is forced to stop spinning under force?

lol I just had the thought one day and I'm not entirely sure how it would work out.

2. Im not going to get involved in this, I can see it heading in the direction of the plane on the treadmill.

3. Theoretically, i don't have a clue. But I reckon that the moon is balanced in place due to all the other gravitational forces on it (eg, from Sun, other planets etc). If you add on a bit of force (pulling it) along with the Earth's gravity, then yes. but veeeeeeeeeeeeeeeeeeeery slowly.

Going to the rotation, that you'll have to ask a real physicist

4. My vote is yes, but assuming the mass of the objects involved it would take you a hell of a long time

5. Originally Posted by unreal
Could you theoretically pull them together with ease considering they are simply objects in space? Or would the entire mass/gravity thing play a role in it? Because otherwise the gravitational pull of the Earth-end of the chain would pull the moon, as the whole 'weightless object regardless of size' theory would come into play.
Don't forget centripedal force - it's this that's stopping them from colliding in the first place - think spinning a bucket of water around in a circle, you are actually pulling on the bucket and if you let go it would go flying. If you did the chain thing you would have to be pulling against this force, and as your pull would be such a small fraction of the forces already in place it would take a long time

Also if we come back to reality and the whole rotation thing is back, when the moon rotates around the Earth and ties the chain around the Earth like a string around a ball (since the Moon rotates around the Earth ofc),
would they slowly come closer together until they collide as the chain length runs out? Or would they alter each other's spin, like as if the Earth's spinning power is greater than the moons, so the moon is forced to stop spinning under force?
Well the moon already doesn't spin relative to the earth - it's orbital period is the same as it's rotational period - that's why the same side of the moon is always facing the earth. The reason for that is the 'tidal' forces that the earth exerts on the moon, slightly stretching it and keeping it aligned.

However the earth does spin, so what would happen would depend on the relative forces. If the pull on the chain (earths rotational force) was greater than the tidal forces then the moon would just tilt towards the edge of the earth that the chain trails from. If the tidal force was greater then it would stay pointing the same direction and the earth would stop spinning relative to the moon.

There is no way that this would be possible to do because it would be impossible to create an anchor point on the moon for the chain as everyone knows, the moon is made of cheese.

7. What's the chain made of?

And what's providing the thrust?

And will fog make any difference?

8. I would start with the chain would most likely break, as the Earth would be pulling it one way and the moon the other through gravity. Thicker chain may help, but thicker = more weight and therefore more effect from gravity.

Assuming it didn't break though, I would take a stab at them pulling together themselves as they each try to pull the chain down. If the chain slackened then more chain-mass would be closer to each body and therefore the effect of gravity would increase.

I'm waiting for page 20 where someone suddenly pulls the whole OP apart word for word and decides we've all been going about it the wrong way!

Edit: Clunk strikes again!

9. Originally Posted by Elyk
Theoretically, i don't have a clue.

ROFL bang on!

10. This thread is a lot more funny if you dont read the title properly, and substitute "giant chain" with "giant chin"

I was thinking there would be a giant chin hanging from the bottom of the earth somehow with the moon bolted to the other side :/

11. If this WAS true, it would be a great way to destroy earth wouldn't it? Just place a small explosive device on one side of the moon and watch the moon crash into the earth from the safety of your spaceship shaped like a pair of breasts... mwahahahaha.

(nukes would probably work too)

12. Originally Posted by Elyk
Theoretically, i don't have a clue. But I reckon that the moon is balanced in place due to all the other gravitational forces on it (eg, from Sun, other planets etc). If you add on a bit of force (pulling it) along with the Earth's gravity, then yes. but veeeeeeeeeeeeeeeeeeeery slowly.

Going to the rotation, that you'll have to ask a real physicist
Actually the moon is moving away from the earth at about 1" per year. Without the moon our planet wouldn't be habitable. The moon keeps our weather in balance and stops winds blowing out of control.

As for the main question, I won't be getting involved.

13. Originally Posted by Dorza
Actually the moon is moving away from the earth at about 1" per year. Without the moon our planet wouldn't be habitable. The moon keeps our weather in balance and stops winds blowing out of control.

So that's what's wrong!

We must get everybody on the far side of the planet to look up and blow, blow hard! Save our environment!

14. Attempting to seriously answer the question:

The force holding the moon in orbit is gravity - otherwise it would spin off into space in a straight line that it's momentum is taking it. If you then add a chain that - as it rotates around the earth - pulls it towards the earth, I believe it would pull closer to the earth, and not send the earth/moon hurtling like a pair of slippery nun-chucks. This is because the force holding the earth in orbit is the gravitational pull between earth and sun, which is stronger than moon/earth AFAIK.

Also as soon as you pulled the moon slightly closer to the earth the gravity would start to increase (gravitational force is inversely proportional to distance) and pull it in even faster down to crash into the earth.

15. Originally Posted by chicken
We must get everybody on the far side of the planet to look up and blow, blow hard! Save our environment!
Last time that happened, we ended up with a big hole in the ozone layer.

16. Originally Posted by Rack
Attempting to seriously answer the question:

The force holding the moon in orbit is gravity - otherwise it would spin off into space in a straight line that it's momentum is taking it.

No, really it is moving away into space. Nothing significant but it is happening.8th paragraph down

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