Rope Around The Earth

Imagine there s a rope around the equator of an earth sized sphere making it around 25 000 miles long.

Rope around the earth.

Divide again by pi to get the earth s radius 6 370km. How much longer must it be for it to be one foot off the ground all the way around the equator. A corollary is that to raise the original string 16 cm 6 3 in off the ground all the way around the equator only about 1 metre 3 ft 3 in needs to be added. This below is one answer i saw.

Let c be the earth s circumference r be its radius c be the added string length and r be the added radius. The rope around the earth puzzle. 15cm that s how far off the ground we re lifting the string remember out of 6 370km is close. The idea is to imagine the earth is a cube or just a square really and ask yourself if you added say 8 feet to the rope how far would that raise it above the square earth.

As a circle of radius r has a circumference of 2 π r regardless of the value of c. 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. 2pi or approximately 6 28 feet for both the basketball and the earth. 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.

From the diagram it s pretty clear it s one foot. If you put 1 metre high sticks right around the equator and lay the rope on. Now imagine the rope is made just one meter longer and lifted uniformly off the surface until it is once again taught. Student answer form blackline master rope around the world you have a piece of rope that just fits around the earth.