Ropes around the Equator - Solution

Main Puzzles Page

Solution

The longer rope is approximately A) 6 feet longer than the shorter rope.

Explanation

Let the radius of the earth be R feet.

The length of the first rope is 2pR feet.

Since the second rope is of radius (R+1) feet, the length of the second rope is 2p(R+1) feet.

So, the difference in length between the two ropes is:

 

   2p(R+1) - 2pR feet

 

= 2pR + 2p - 2pR feet

 

= 2p feet

 

» 6 feet

Note

As you can see, the radius of the circle is irrelevant which is rather counter-intuitive!

Back to Main Puzzles Page