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MCQs

Total Questions : 47 | Page 3 of 5 pages
Question 21. A plate 0.3 m long is placed at zero angle of incidence in a stream of 15 degree Celsius water moving at 1 m/s. Find out the maximum boundary layer thickness. For water at 15 degree Celsius. For water at 15 degree Celsius
p = 998.9 kg /m³
µ = 415.85 * 10¯² kg/hr m
  1.    4.945 m
  2.    3.945 m
  3.    2.945 m
  4.    1.945 m
 Discuss Question
Answer: Option C. -> 2.945 m
Answer: (c).2.945 m
Question 22. Air at 25 degree Celsius flows over a flat surface with a sharp leading edge at 1.5 m/s. Find the boundary layer thickness at 0.5 from the leading edge. For air at 25 degree Celsius, kinematic viscosity = 15.53* 10n¯⁶ m²/s
  1.    4.1376 cm
  2.    3.1376 cm
  3.    2.1376 cm
  4.    1.1376 cm
 Discuss Question
Answer: Option D. -> 1.1376 cm
Answer: (d).1.1376 cm
Question 23. Boundary layer thickness is given by
  1.    δ = 5.64 x/ (Re) ½
  2.    δ = 5.64 x/ (Re) ½
  3.    δ = 6.64 x/ (Re) ½
  4.    δ = 7.74 x/ (Re) ½
 Discuss Question
Answer: Option B. -> δ = 5.64 x/ (Re) ½
Answer: (b).δ = 5.64 x/ (Re) ½
Question 24. Air at 25 degree Celsius flows over a flat surface with a sharp leading edge at 1.5 m/s. Find the value of Reynolds number. For air at 25 degree Celsius, kinematic viscosity = 15.53* 10n¯⁶ m²/s
  1.    38694
  2.    12846
  3.    48294
  4.    76386
 Discuss Question
Answer: Option C. -> 48294
Answer: (c).48294
Question 25. Consider the diagram given below and identify the correct optionConsider The Diagram Given Below And Identify The Correct Op...
  1.    The velocity gradient is zero everywhere
  2.    The velocity profile changes at every instant of time
  3.    Boundary layers from the pipe walls meet the pipe anywhere
  4.    Thickness of the boundary layer is limited to the pipe radius
 Discuss Question
Answer: Option D. -> Thickness of the boundary layer is limited to the pipe radius
Answer: (d).Thickness of the boundary layer is limited to the pipe radius
Question 26. A plate 0.3 m long is placed at zero angle of incidence in a stream of 15 degree Celsius water moving at 1 m/s. Find out the maximum value of the normal component of velocity at thr trailing edge of the plate. For water at 15 degree Celsius
p = 998.9 kg /m³
µ = 415.85 * 10¯² kg/hr m
  1.    1.6885 * 10¯² m/s
  2.    1.6885 * 10¯³ m/s
  3.    1.6885 * 10¯⁴ m/s
  4.    1.6885 * 10¯⁵ m/s
 Discuss Question
Answer: Option B. -> 1.6885 * 10¯³ m/s
Answer: (b).1.6885 * 10¯³ m/s
Question 27. A two pass surface condenser is required to handle the exhaust from a turbine developing 15 MW with specific steam consumption of 5 kg/k W h. The quality of exhaust steam is 0.9, the condenser vacuum is 66 cm of mercury while the bar meter reads 76 cm of mercury. The condenser tubes are 28 mm inside diameter, 4 mm thick and water flows through tubes with a speed of 3 m/s and inlet temperature 20 degree Celsius. All the steam is condensed, the condensate is saturated water and temperature of cooling water at exit is 5 degree Celsius less than the condensate temperature. Assuming that overall coefficient of heat transfer is 4 k W/m² degree, determine the mass of cooling water circulated.A Two Pass Surface Condenser Is Required To Handle The Exhau...
  1.    746.13 kg/s
  2.    646.13 kg/s
  3.    546.13 kg/s
  4.    446.13 kg/s
 Discuss Question
Answer: Option D. -> 446.13 kg/s
Answer: (d).446.13 kg/s
Question 28. Which field is set up when a fluid flows past a heated or cold surface?
  1.    Energy
  2.    Temperature
  3.    Mass
  4.    Time
 Discuss Question
Answer: Option B. -> Temperature
Answer: (b).Temperature
Question 29. The convection of energy reduces the outward conduction in the fluid so temperature gradient
  1.    Decreases
  2.    Increases
  3.    Constant
  4.    Becomes twice
 Discuss Question
Answer: Option A. -> Decreases
Answer: (a).Decreases
Question 30. The thickness of thermal boundary layer is arbitrarily defined as the distance from the plate surface at which
  1.    t S – t/t S – t INFINITY = 0.34
  2.    t S – t/t S – t INFINITY = 0.10
  3.    t S – t/t S – t INFINITY = 0.99
  4.    t S – t/t S – t INFINITY = 0.87
 Discuss Question
Answer: Option C. -> t S – t/t S – t INFINITY = 0.99
Answer: (c).t S – t/t S – t INFINITY = 0.99

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