MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 75 Mcqs, each offering curated multiple-choice questions to sharpen your Heat Transfer knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
Navier-Stokes equations represent: |
| A. | mass conservation |
| B. | vorticity conservation |
| C. | energy conservation |
| D. | viscosity |
| Answer» B. vorticity conservation | |
| 52. |
If the Reynolds number for a flow is 3000, then the type of flow is____. |
| A. | laminar |
| B. | transitional |
| C. | turbulent |
| D. | vortex |
| Answer» C. turbulent | |
| 53. |
A pipeline 20 cm in diameter, 70 m long conveys oil of specific gravity 0.95 and viscosity 0.23 Ns/m2, If the velocity of oil is 1.38 m/s, find the difference in pressure between the two ends of the pipe? |
| A. | 2.52 m |
| B. | 3.75 m |
| C. | 1.21 m |
| D. | 1.91 m |
| Answer» E. | |
| 54. |
A sphere of diameter 30 cm is moving with a uniform velocity of 4 m/s. The dynamic viscosity and specific gravity of the liquid are given as 0.8 poises and 0.9 respectively. What is the value of the Reynolds number? |
| A. | 135 |
| B. | 10000 |
| C. | 13500 |
| D. | 15000 |
| Answer» D. 15000 | |
| 55. |
A crude oil having a specific gravity of 0.9 flows through a pipe of diameter 0.15 m at the rate of 8 lps. If the value of μ is 0.3 Ns/m2, the Reynolds number will be nearly |
| A. | 295 |
| B. | 235 |
| C. | 205 |
| D. | 165 |
| Answer» D. 165 | |
| 56. |
For laminar flow through a round pipe, the shear stress |
| A. | remains constant over the cross-section |
| B. | Varies linearly with the radial distance |
| C. | Must be zero at all points |
| D. | Varies parabolically with radial distance |
| Answer» C. Must be zero at all points | |
| 57. |
A fluid flowing steadily in a circular pipe of radius R has a velocity that is everywhere parallel to the axis (centerline) of the pipe. The velocity distribution along the radial direction is \({{{V_r}}} = U\left( {1 - \frac{{{r^2}}}{{{R^2}}}} \right)\), where r is the radial distance as measured from the pipe axis and U is the maximum velocity at r = 0. The average velocity of the fluid in the pipe is |
| A. | \((\frac{5}{6})U\) |
| B. | \(\frac{U}{4}\) |
| C. | \(\frac{U}{3}\) |
| D. | \(\frac{U}{2}\) |
| Answer» E. | |
| 58. |
If the Reynolds number is less than 2000, the flow in pipe is - |
| A. | Transitional from laminar to turbulent |
| B. | Turbulent |
| C. | Inviscid |
| D. | Laminar |
| Answer» E. | |
| 59. |
Match the following non-dimensional numbers the corresponding definitions:Non-dimensional numberDefinitionPReynolds number1(Buoyancy force)/ (Viscous force)QGrashof number2(Momentum diffusivity)/ (Thermal diffusivity)RNusselt number3(Inertia force)/ (Viscous force)SPrandtl number4(Convective heat transfer)/ (Conduction heat transfer) |
| A. | P-1, Q-3, R-2, S-4 |
| B. | P-3, Q-1, R-2, S-4 |
| C. | P-4, Q-3, R-1, S-2 |
| D. | P-3, Q-1, R-4, S-2 |
| Answer» E. | |
| 60. |
In a laminar flow between two fixed plates held parallel to each other at a distance d, the shear stress is:1) Maximum at plane \(\frac{d}{2}\) away from each plate and zero at the plate boundaries.2) Zero throughout the passage.3) Maximum at the plate boundaries and zero at plane \(\frac{d}{2}\) away from each plate.Which of the above statements is/are correct? |
| A. | 1 only |
| B. | 3 only |
| C. | 2 only |
| D. | 1, 2 and 3 |
| Answer» C. 2 only | |
| 61. |
For flow-through soils, the flow is laminar when the Reynold number is: |
| A. | greater than 2000 |
| B. | less than 2500 |
| C. | greater than unity |
| D. | less than unity |
| Answer» E. | |
| 62. |
In the context of laminar flow, which of the following statements is the most appropriate? |
| A. | Flow is always through small tanks. |
| B. | Particles move in a turbulent order. |
| C. | Laminar flow is observed in high viscous fluids at low velocity. |
| D. | There will be an exchange of momentum from fluid particles of one layer to another layer. |
| Answer» D. There will be an exchange of momentum from fluid particles of one layer to another layer. | |
| 63. |
Laminar developed flow at an average velocity of 5 m/s occurs in a pipe of 10 cm radius. The velocity at 5 cm radius is |
| A. | 7.5 m/s |
| B. | 10 m/s |
| C. | 2.5 m/s |
| D. | 5 m/s |
| Answer» B. 10 m/s | |
| 64. |
Noise level in case of an aircraft is |
| A. | generally, less than 100 db |
| B. | generally, more than 100 db |
| C. | always more than 100 db |
| D. | in the range of 60-80 db |
| Answer» D. in the range of 60-80 db | |
| 65. |
If a thin plate is held normal to the flow, the viscous drag on it is ______ |
| A. | Maximum |
| B. | Minimum |
| C. | Zero |
| D. | None of the above |
| Answer» D. None of the above | |
| 66. |
In steady laminar flow of a liquid through a circular pipe of internal diameter D carrying a constant discharge, the hydraulic gradient will be |
| A. | proportional to D2 |
| B. | proportional to D3 |
| C. | inversely proportional to D2 |
| D. | inversely proportional to D3 |
| Answer» D. inversely proportional to D3 | |
| 67. |
An oil of kinematic viscosity of 0.5 stokes flows through a pipe of 20 cm diameter. What is the velocity if the flow is critical? |
| A. | 0.5 m/s |
| B. | 0.9 m/s |
| C. | 1.5 m/s |
| D. | 2 m/s |
| Answer» B. 0.9 m/s | |
| 68. |
Engine oil flows in a 15 cm diameter horizontal tube with a velocity of 1.3 m/s, experiencing a pressure drop of 12 kPa.The pumping power required to overcome this pressure drop is. |
| A. | 190 W |
| B. | 276 W |
| C. | 407 W |
| D. | 655 W |
| Answer» C. 407 W | |
| 69. |
For a fully developed laminar flow of water (dynamic viscosity 0.001 Pa-s) through a pipe of radius 10 cm, the axial pressure gradient is -10 Pa/m. The magnitude of maximum velocity (in m/s) is |
| A. | 25 |
| B. | 50 |
| C. | 75 |
| D. | 100 |
| Answer» B. 50 | |
| 70. |
In a laminar flow of a liquid down an inclined plane, the surface velocity is found to be 60 cm/s. the average velocity of the flow in cm/s is: |
| A. | 40 |
| B. | 120 |
| C. | 15 |
| D. | 30 |
| Answer» B. 120 | |
| 71. |
Consider flow of oil and water through a channel; the boundary conditions at the interface are |
| A. | Velocity and shear stress are continuous |
| B. | Shear stress is continuous and velocity is discontinuous |
| C. | Shear stress is zero and velocity is continuous |
| D. | Shear stress is zero |
| Answer» C. Shear stress is zero and velocity is continuous | |
| 72. |
Glycerine (μ = 1.50 Pa.s: ρ = 1260 kg/m3) flows at a velocity of 6.0 m/s in 10 cm diameter pipe. Head loss in a length of 7 m pipe will be (g = 10 m/s2). |
| A. | 14 m |
| B. | 16 m |
| C. | 7 m |
| D. | 8 m |
| Answer» C. 7 m | |
| 73. |
Hydraulic diameter of square duct is given by |
| A. | Side of the square |
| B. | 2 × Side of the square |
| C. | 1.5 × Side of the square |
| D. | .5 × Side of the square |
| Answer» B. 2 × Side of the square | |
| 74. |
Oil at 20°C (density = 870 kg/m3 and velocity = 0.104 kg/m-s) flow at 1.1 m3/hr through a horizontal pipe with diameter d = 2 cm and length L = 12 m. Find the Reynolds number for the flow. |
| A. | 104 |
| B. | 163 |
| C. | 208 |
| D. | 78 |
| Answer» C. 208 | |
| 75. |
A rectangular plate of mass M slides down, on a film of oil, at a uniform velocity on an inclined surface sloping at 30o. Under this condition: |
| A. | The resistance due to viscosity of oil = M |
| B. | There is no resistance to motion as it slides down |
| C. | The viscous resistance to motion = M.sin.30 |
| D. | The coefficient of friction = 0.5 |
| Answer» D. The coefficient of friction = 0.5 | |