##### Q41. An incompressible fluid flows over a flat plate with zero pressure gradient. The boundary layer thickness is 1 mm at a location where the Reynolds number is 1000. If the velocity of the fluid alone is increased by a factor of 4, then the boundary layer thickness sat the same location, in mm will be

(a) 4
(b) 2
(c) 0.5
(d) 0.25.                                                                                                                    (GATE-ME-2012)

Ans: (c) 0.5

##### Q42. The power transmitted by a flowing fluid through a pipe will be maximum if head loss due o friction in pipe is

(a) equal to total head at inlet
(b) half the total head at inlet
(c) one-third of the total head at inlet
(d) one-fourth of the total head at inlet.

Ans: (c) one-third of the total head at inlet

##### Q43. A water container is kept on a weighing balance. Water from a tap is falling vertically into the container with a volume flow rate of ‘Q’; the velocity of the water when it hits the water surface is ‘U’. At a particular instant of time the total mass of the container and water is ‘m’. The force registered by the weighing balance at this instant of time is

(a) mg + ρQU
(b) mg + 2ρQU
(c) mg + ρQU2/2
(d) ρQU2/2.                                                                                                            (GATE-ME-2003)

Ans:  (a) mg + ρQU

(a) x4/5
(b) x1/2
(c) x1/5
(d) x2/5

Ans:  (a) x4/5

##### Q45. If there are ‘m’ physical quantity and ‘n’ fundamental dimensions in a particular process, the number of non-dimensional parameters is

(a) m + n
(b) m × n
(c) m – n
(d) m/n.                                                                                                              (GATE-ME-2002)

Ans:  (c) m – n

##### Q46. Maximum velocity of a one-dimensional incompressible fully developed viscous flow, between two fixed parallel plates, is 6 ms–1. The mean velocity (in ms–1) of the flow is

(a) 2
(b) 3
(c) 4
(d) 5.                                                                                                              (GATE-ME-2010)

Ans:  (c) 4

##### Q47. If ‘x’ is the distance measured from the leading edge of a flat plate, then laminar boundary layer thickness varies as

(a) 1/x
(b) x4/5
(c) x2
(d) x1/2.                                                                                                             (GATE-ME-2002)

Ans:  (d) x1/2

##### Q48. A circular plate 1 m in diameter is submerged vertically in water such that its upper edge is 8 m below the free surface of water. The total hydrostatic pressure force on one side of plate is

(a) 6.7 kN
(b) 65.4 kN
(c) 45.0 kN
(d) 77.0 kN.                                                                                             (GATE-ME-1988)

Ans:  (b) 65.4 kN

##### Q49. A centrifugal pump is required to pump water to an open water tank situated 4 km away from the location of the pump through a pipe of diameter 0.2 m having Darcy’s friction factor for 0.01. The average speed of water in the pipe is 2 m/s. If it is to maintain a constant head of 5 m in the tank, neglecting other minor losses, the absolute discharge pressure at the pump exist is

(a) 0.449 bar
(b) 5.503 bar
(c) 44.911 bar
(d) 55.203 bar.                                                                                                             (GATE-ME-2004)

Ans:  (b) 5.503 bar

##### Q50. At a hydro electric power plant site, available head and flow rates are 24.5 m and 10.1 m3/s respectively. If the turbine to be installed is required to run at 4.0 revolution per second (rps) with an overall efficiency of 90%, then suitable type of turbine for this site is

(a) Francis
(b) Kaplan
(c) Pelton
(d) Propeller.                                                                                              (GATE-ME-2004)

Ans:  (a) Francis

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Hydraulics and Fluid mechanics MCQ-Section-1

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Hydraulics and Fluid mechanics MCQ-Section-3

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Hydraulics and Fluid mechanics MCQ-Section-5

Hydraulics and Fluid mechanics MCQ-Section-6