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Math Forum » Discussions » Math Topics » geometry.puzzles.independent

Topic: Cable around the Equator
Replies: 10   Last Post: Jun 17, 2012 2:29 PM

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Alan Lipp

Posts: 41
Registered: 12/6/04
Re: Cable around the Equator
Posted: Nov 4, 1996 8:05 AM
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On Mon, 4 Nov 1996, mfr1 wrote:

> Ma Bell want to place a telephone cable around the equator. She adds 50
> feet to the length of the cable beyond what is required. This slack in the
> cable allows the cable to be strung up above the ground. How high up from
> the surface of the earth will the cable stand? You can assume that the
> earth is a perfect sphere.
>
> In your mind, run a sanity check on your answer to see if it makes sense.
>
Surprisingly, you will be able to walk under the cble easilty. Since the
circumference of a circle is C = 2piR, each increase in R obf 1 foot
increases the circumference by 2pi feet. since the cable has been
increased by 50 feet the radius of the cable-circle will be increased by
50/2pi or about 8 feet!

Alan Lipp

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