Consider a bucket of water with two holes of equal area through which water is discharged. The water can flow out through hole ( B ), at the bottom, or through the down-spout, which begins at the top ( T ) and has its opening the same distance below the water level as the center of hole ( B).

  \-------------------------/
   \                       /
    \                     /__
     \                  T/--+|
      \                 /   ||
       \               /    ||
    ____\             /     ||
    -----\B          /      ||
          \---------/

Ignoring any friction effects, out of which opening will the water flow faster, and why?

Will the flow rate through T increase if you extend it further down for another 100ft? No! Imagine cutting the vertical section laterally in half and (slowly:) removing the parts. Nothing would change. The vertical section of T doesn't matter since water in it is in free fall. It would  only matter if there was a U turn at the end of it. In real world things are different because of friction. Then the vertical section would make a difference depending its diameter. B is the correct answer.

Edited on September 29, 2006, 12:37 pm

Posted by Art M on 2006-09-29 11:58:06