A roof drains into a gutter, which feeds the water into a downspout with a square cross section (4 in.  4 in.). The discharge end of the downspout is 12 ft below the entrance, and terminates in a 908...

A roof drains into a gutter, which feeds the water into a downspout with a square cross section (4 in.  4 in.). The discharge end of the downspout is 12 ft below the entrance, and terminates in a 908 mitered (one weld) elbow. The downspout is made of smooth sheet metal.

(a) What is the capacity of the downspout, in gpm?

(b) What would the capacity be if there were no elbow on the end?