# 300+ TOP FLUID MECHANICS Multiple Choice Questions and Answers

91. The length of a pipe is 1 km and its diameter is 20 cm. If the diameter of an equivalent pipe is 40 cm, then its length is
a) 32 km
b) 20 km
c) 8 km
d) 4 km
Ans: a
92. Two pipes of same length and diameters d and 2d respectively are connected in series. The diameter of an equivalent pipe of same length is
a) less than d
b) between d and 1.5 d
c) between 1.5 d and 2d
d) greater than 2d
Ans: a
93. The horse power transmitted through a pipe is maximum when the ratio of loss of head due to friction and total head supplied is
a) 1/3
b) 1/4
c) 1/2
d) 2/3
Ans: a
94. The boundary layer thickness at a distance of l m from the leading edge of a flat plate, kept at zero angle of incidence to the flow direction, is O.l cm. The velocity outside the boundary layer is 25 ml sec.
The boundary layer thickness at a distance of 4 m is
a) 0.40 cm
b) 0.20 cm
c) 0.10 cm
d) 0.05 cm
Assume that boundary layer is entirely laminar.
Ans: b
95. Drag force is a function of
i) projected area of the body
ii) mass density of the fluid
iii) velocity of the body