Help... 1st get 10 points!?

ume the earth is a perfect sphere and its cirference at the equator is exactly 25000 miles. Imagine that a belt fits exactly around the earth at the equator. Now suppose we lengthen the belt by 20 feet and distribute this extra length equally around the equator. the best wont touch the ground at any point. How much room will be between the ground and the belt.