Footnote †: Unstable Equilibrium
This video is a footnote for the video about the ring around the earth: https://www.youtube.com/watch?v=4xSPlQUejd8 Essentially, a ring around the earth is in unstable equilibrium, so it would...
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As several people have pointed out, a very strong ring around a spherically symmetricobject is in an unstable gravitational equilibrium, which means that if it stays perfectly put,it’s fine, but if it gets nudged even just slightly off its perfectly centered position,it will then get pulled farther and farther from that position, since the part now closerto the earth gets pulled more strongly toward the earth than the part now farther from earth.So, it’s just like a perfectly balanced pencil.
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As several people have pointed out, a very strong ring around a spherically symmetricobject is in an unstable gravitational equilibrium, which means that if it stays perfectly put,it’s fine, but if it gets nudged even just slightly off its perfectly centered position,it will then get pulled farther and farther from that position, since the part now closerto the earth gets pulled more strongly toward the earth than the part now farther from earth.So, it’s just like a perfectly balanced pencil.
