Fluid Mechanics MCQs

71. The pressure at the summit of a syphon is_______________?

A. equal to atmospheric

B. less than atmospheric

C. more than atmospheric

D. none of the above

✅ The correct answer is option B.

72. The boundary layer thickness in turbulent flow varies as______________?

A. x”7

B. x,/2

C. x4/5

D. x3/5

✅ The correct answer is option C.

73. The pitot tube is used to measure________________?

A. velocity at stagnation point

B. stagnation pressure

C. static pressure

D. dynamic pressure

✅ The correct answer is option B.

74. Pascal-second is the unit of______________?

A. pressure

B. kinematic viscosity

C. dynamic viscosity

D. surface tension

✅ The correct answer is option C.

75. When an ideal fluid flows past a sphere________________?

A. highest intensity of pressure occurs around the circumference at right angles to flow

B. lowest pressure intensity occurs at front stagnation point

C. lowest pressure intensity occurs at rear stagnation point

D. total drag is zero

✅ The correct answer is option D.

76. In which of the following the friction drag is generally larger than pressure drag?

A. a circular disc or plate held normal to flow

B. a sphere

C. a cylinder

D. an airfoil

✅ The correct answer is option D.

77. The correct relationship among displacement thickness d, momentum thickness m and energy thickness e is_________________?

A. d > m > e

B. d > e > m

C. e > m > d

D. e > d > m

✅ The correct answer is option D.

78. An open cubical tank of 2 m side is filled with water. If the tank is rotated with an acceleration such that half of the water spills out, then the acceleration is equal to_______________?

A. g/3

B. g/2

C. 2g/3

D. g

✅ The correct answer is option D.

79. The motion of air mass in a tornado is a________________?

A. free vortex motion

B. forced vortex motion

C. free vortex at center and forced vortex outside

D. forced vortex at center and free vortex outside

✅ The correct answer is option D.

80. In a Sutro weir, the discharge is proportional to________________?

A. H1/2

B. H3/2

C. H5/2

D. H

✅ The correct answer is option D.