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# Physics hmmm watch

1. If you were, hypothetically, to stick a pulley on the moon and throw a length of rope around it long enough that both ends touched the ground in London, and then pulled on one end of the rope, would the other end move immediately?
2. i think by the times the moved round its orbit one end mignt be in america.. plus it would probably freeze up and snap when you pulled it....plus the mass of rope youre pulling might weigh a bit....its all questions
3. (Original post by fishpaste)
If you were, hypothetically, to stick a pulley on the moon and throw a length of rope around it long enough that both ends touched the ground in London, and then pulled on one end of the rope, would the other end move immediately?
If the string was taught, yes
4. (Original post by fishpaste)
If you were, hypothetically, to stick a pulley on the moon and throw a length of rope around it long enough that both ends touched the ground in London, and then pulled on one end of the rope, would the other end move immediately?
No, the other end would move about (as in a tiny bit less than) 2r/c seconds later, where r is the moon's orbital radius. If it moved immediately, you would be transferring information faster than the speed of light, which is (questionably) impossible.

It's almost instant, but there would be a slight time lag, like when you have an elastic band around both hands, if you move your left hand further left there is an amount of time taken for the additional force in the tension of the elastic band to be transferred to your right hand - this is like what the bonds in the rope you use do.
5. (Original post by mik1a)
No, the other end would move about (as in a tiny bit less than) 2r/c seconds later, where r is the moon's orbital radius. If it moved immediately, you would be transferring information faster than the speed of light, which is (questionably) impossible.

It's almost instant, but there would be a slight time lag, like when you have an elastic band around both hands, if you move your left hand further left there is an amount of time taken for the additional force in the tension of the elastic band to be transferred to your right hand - this is like what the bonds in the rope you use do.
you're also assuming the rope is completely inextensible, which it wont be. the actual time it would take would be dependent on the speed of longitudinal waves through the rope

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