A pump is used to circulate oil in an engine. If the diameter of the tube connecting the pump to the engine is increased by a factor of 2, the ration of the resulting pressure to the initial pressure in the pipe is
A) 1/32.
B) 1/16.
C) 1/8.
D) 1/2.
E) 1/4.

Question

Quizplus · Accepted Answer

The pressure in a pipe is inversely proportional to the fourth power of the diameter (according to the Hagen-Poiseuille equation for laminar flow). If the diameter is increased by a factor of 2, the pressure decreases by a factor of 2^4 = 16. Thus, the ratio of the resulting pressure to the initial pressure is 1/16.

A Pump Is Used to Circulate Oil in an Engine