Calculating Work:
A water well has an eight-inch casing (diameter) and is 175 feet deep. The water is 25 feet from the top of the well. Determine the amount of work done in pumping the well dry, assuming that no water enters it while it is being pumped.

Question

Calculating Work: 
A water well has an eight-inch casing (diameter) and is 175 feet deep. The water is 25 feet from the top of the well. Determine the amount of work done in pumping the well dry, assuming that no water enters it while it is being pumped.

sw050399 · Answer

I have the answer for the problem, but I am unsure how they get the 1/3 in the first line.

anonymous · Answer

The diameter is 8 inches, so the radius is 4 inches, so if we're working in feet, the radius is 1/3.