Imagine a "rope" (for want of a better word) is wrapped all the way around the Earth, to the point that you can hold both ends.

There is no slack on the rope, i.e. it doesn't stretch. It also isn't caught on anything on the Earth's surface and no friction applies to it, if that matters.

If I pull one end in one hand, would the other end move instantaneously? I don't see why it wouldn't but it's hard to imagine it moving straight away when it's wrapped around such a distance.

I'm no physicist so I might not be accounting for something obvious, or it is just that simple. Because of this I also wasn't sure how to tag this. Thanks.

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    $\begingroup$ Hi Neil. The duplicate I've suggested uses a pole not a rope but the principle is the same. In both cases the motion travels long the rope or pole at the speed of sound so it isn't instantaneous. $\endgroup$ Aug 22 '18 at 15:31

The other end would not move instantaneously. The speed at which the signal of you moving one hand will move is at the speed of sound in the rope. In fact, the speed of propagation of any signal cannot be faster than the speed of light.

You can see this easily by just wiggling a rope up and down. It takes time for the other end of the rope to move. The same is true for really long ropes as well. You could also get a really long slinky and push/pull on it. It takes time for the longitudinal wave to propagate.


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