Question

7. Imagine a rope tied around the earth at the equator. How much rope would you need to add in order to raise it one foot above the ground/water around the entire equator? You can use 3961.3 miles or 20915664 feet as the radius of the earth, although you don't need that for this problem.

Answer 1

r0=earth radius

r1=earth radius + 1 foot

`\begin{gathered} l0=2\pi r0 \\ l1=2\pi(r0+1) \end{gathered}`

now we are going to calculate how much rope we need in order to raise it one foot

`\begin{gathered} l1-l0= \\ =2\pi r0-2\pi(r0+1) \\ =2\pi \end{gathered}`

so we need 2 pi feet