If a girl 5 feet tall could walk around the equator, how many feet further would the top of her head travel than her feet? Assume that the earth is a sphere. Express your answer in terms of pi.
Assume that the radius of the Earth is r feet.
She travels the circumfrence of the Earth, which is 2*pi*r.
However, when we count her head instead of her feet, the radius gets increased by 5 feet.
(2*pi*(r+5)) - (2*pi*r) = 10pi