61. The maximum thickness of boundary layer in a pipe of radius r is____________________?
A. 0
B. r/2
C. r
D. 2r
✅ The correct answer is option C.
Fluid Mechanics MCQs
62. The hydraulic grade line is_________________?
A. always above the centre line of pipe
B. never above the energy grade line
C. always sloping downward in the direction of flow
D. all of the above
✅ The correct answer is option B.
63. A vertical rectangular plane surface is submerged in water such that its top and bottom surfaces are 1.5 m and 6.0 m res-pectively below the free surface. The position of center of pressure below the free surface will be at a distance of________________?
A. 3.75 m
B. 4.0 m
C. 4.2m
D. 4.5m
✅ The correct answer is option C.
64. The velocity distribution for laminar flow through a circular tube__________________?
A. is constant over the cross-section
B. varies linearly from zero at walls to maximum at centre
C. varies parabolically with maximum at the centre
D. none of the above
✅ The correct answer is option C.
65. Ay between two stream lines represents________________?
A. velocity
B. discharge
C. head
D. pressure
✅ The correct answer is option B.
66. If the velocity is zero over half of the cross-sectional area and is uniform over the remaining half, then the momentum correction factor is_______________?
A. 1
B. 4/3
C. 2
D. 4
✅ The correct answer is option C.
67. Newton’s law of viscosity relates________________?
A. intensity of pressure and rate of angular deformation
B. shear stress and rate of angular deformation
C. shear stress, viscosity and temperature
D. viscosity and rate of angular deformation
✅ The correct answer is option B.
68. In a two dimensional incompressible steady flow around an airfoil, the stream lines are 2 cm apart at a great distance from the airfoil, where the velocity is 30 m/sec. The velocity near the airfoil, where the stream lines are 1.5 cm apart, is_________________?
A. 22.5 m/sec
B. 33 m/sec
C. 40 m/sec
D. 90 m/sec
✅ The correct answer is option C.
69. For hydro-dynamically smooth boundary, the friction coefficient for turbulent flow is_______________?
A. constant
B. dependent only on Reynolds number
C. a function of Reynolds number and relative roughness
D. dependent on relative roughness only
✅ The correct answer is option B.
70. If a sphere of diameter 1 cm falls in castor oil of kinematic viscosity 10 stokes, with a terminal velocity of 1.5 cm/sec, the coefficient of drag on the sphere is________________?
A. less than 1
B. between 1 and 100
C. 160
D. 200
✅ The correct answer is option C.