Rope Around The Earth Add 1 Meter

Suppose you tie a rope tightly around the earth s equator.

Rope around the earth add 1 meter. How high is that. You add an extra 3 feet to the length. Imagine a rope that fits snugly all the way around the earth like a ring on a person s finger. Imagine a rope tied around the earth s equator like a ring on a person s finger.

If you put 1 metre high sticks right around the equator and lay the rope on top how much longer does the rope need to be to make ends meet. Then imagine placing this longer rope back around the earth s equator. Now imagine the rope is made just one meter longer and lifted uniformly off the surface until it is once again taught. The string is now rearranged so that it is at a uniform height above the equator.

Now untie the rope and add an extra 1 meter of rope and make it a perfect circle and place it around the. In a common version of this puzzle string is wrapped around the equator of a perfectly spherical earth. From there it s not hard to believe that adding 3 feet to a rope around the actual earth would raise it almost 6 inches. If you have reasoned the answer and can t believe it you are probably right.

Now let us tie a rope tightly around its equator. This string is cut and a piece 1 metre 3 ft 3 in in length is added in. The radius of earth is 6371 km approx. Divide again by pi to get the earth s radius 6 370km.

Now imagine lifting off this very long rope don t ask me how cutting it somewhere so as to stitch into it exactly one meter of extra rope. In fact this brain teaser requires neither an exact measurement of the earth s circumference which in fact varies by many kilometers depending on which circumference you measure nor even an assumption that the earth has a circular cross sect. From the diagram it s pretty clear it s one foot. This puzzle is somewhat counter intuitive.

15cm that s how far off the ground we re lifting the string remember out of 6 370km is close to one part in forty million. What will its height be above the surface.