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Solve This: Going to Any Lengths Wavebreakmedia Ltd/Wavebreak Media/Thinkstock

Solve This: Going to Any Lengths

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Assume the earth is 25k miles circumference at the equator and is perfectly smooth. Then a transmission cable laid on the ground and circling the earth at the equator would have a length of 25k miles. Now suppose we want to provide a 1 foot line to ground clearance all the way around the earth.

Assuming no sag, approximately how much extra cable would be required?

  • 6.3 ft
  • 28.4 miles
  • 3.14 ft
  • 12.5 k miles
  • none of these. See my answer below
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