Question

An ideal fluid flows through a pipe made of two sections with diameters of 1.0 and 3.0 inches, respectively. What is the ratio of the speed of the fluid through the 3.0-inch section to the speed of the fluid through the 1.0-inch section?
A. 1 : 3
B. 1 : 6
C. 1 : 9
D. 3 : 1
E. 9 : 1

Answer 1

it is related by the square of the inverse, since the 3" pipe has a cross-section area 9 times the 1" pipe.

So, (C)

Answer 2

density1*area1*velocity1=density2*area2*velocity2

If the density is constant, then

area1/area2=velocity2/velocity1
(diameter1/diameter2)^2=v2/v2