+355 Imagine the Earth is a perfectly round sphere, and that you tie a string around the center of the Earth along the equator. The string lies on top of the ground and the oceans. (But since the Earth is a perfect sphere, there are no mountains, etc.) You then get another string longer than the one tied around the Earth. You tie this string in a circle around the Earth as well, but since it is longer, it is above the surface of the Earth and is supported on little platforms that keep the shape of the string perfectly circular. How tall do the platforms need to be? In meters
