XPost: sci.space.policy, sci.physics   
   From: alain245@videotron.ca   
      
   On Jun/22/2018 à 5:45 PM, JF Mezei Wrote :   
   > On 2018-06-22 07:18, Jeff Findley wrote:   
   >   
   >> Because it's flexible, duh.  Imagine that you took 10 meters of fishing   
   >> line with a weight at the bottom then cut it in the middle.  Would it   
   >> stay straight as it fell?  Try it!   
   >   
   >   
   > This does not consider/test the issue that the top of the cable is   
   > travelling at faster speed and as it is being pulled down, will   
   > accelerate further.  If the top of the cable wants to travel faster than   
   > the bottom part of cable, a tension will exist which would not exist in   
   > your fishing line example, and that tension should keep the cable straight.   
      
   That tension you talk about is caused by the centrifugal pseudo-force.   
   In the fishing line example Jeff gave there is the gravitational force   
   that should pull the line down.   
      
   In both cases, when the fishing line or the elevator cable snaps the   
   elasticity pulls back with more force than the gravity or centrifugal   
   force. With the caveat that we don't know what material would be used   
   for the hypothetical space elevator, so we don't know how elastic it   
   would be. But I think it is a safe assumption that if such an elevator   
   was to ever be built, the material would be sufficiently elastic for   
   tens of thousands of kilo-meters of it to give a very strong pull back.   
      
      
   Alain Fournier   
      
   --- SoupGate-Win32 v1.05   
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