Hydraulic and Fluid Mechanics

31. A hemispherical tank of radius (R) has an orifice of cross-sectional area (a) at its bottom and is full of liquid. The time required to empty the tank completely is

  1. 14π R1/2/15Cdxa√(2g)
  2. 14π R3/2/15Cdxa√(2g)
  3. 14π R5/2/15Cdxa√(2g)
  4. 14π R7/2/15Cdxa√(2g)

Correct answer: (C)
14π R5/2/15Cdxa√(2g)

32. A hydraulic press has a ram of 15 cm diameter and plunger of 1.5 cm. It is required to lift a weight of 1 tonne. The force required on plunger is equal to

  1. 10 kg
  2. 100 kg
  3. 1000 kg
  4. 1 kg

Correct answer: (A)
10 kg

33. A jet of water discharging from a 40 mm diameter orifice has a diameter of 32 mm at its vena contracta. The coefficient of contraction is

  1. 0.46
  2. 0.64
  3. 0.78
  4. 0.87

Correct answer: (B)
0.64

34. A large Reynold number is indication of

  1. Smooth and streamline flow
  2. Laminar flow
  3. Steady flow
  4. Highly turbulent flow

Correct answer: (D)
Highly turbulent flow

35. A liquid compressed in cylinder has a volume of 0.04 m3 at 50 kg/cm2 and a volume of 0.039 m3 at 150 kg/cm2. The bulk modulus of elasticity of liquid is

  1. 400 kg/cm2
  2. 4000 kg/cm2
  3. 40 x105 kg/cm2
  4. 40 x106 kg/cm2

Correct answer: (B)
4000 kg/cm2

36. A liquid would wet the solid, if adhesion forces as compared to cohesion forces are

  1. Less
  2. More
  3. Equal
  4. Less at low temperature and more at high temperature

Correct answer: (B)
More

37. A manometer is used to measure

  1. Atmospheric pressure
  2. Pressure in pipes and channels
  3. Pressure in Venturimeter
  4. Difference of pressures between two points in a pipe

Correct answer: (B)
Pressure in pipes and channels

38. A metal with specific gravity of 'a' floating in a fluid of same specific gravity 'a' will

  1. Sink to bottom
  2. Float over fluid
  3. Partly immersed
  4. Be fully immersed with top surface at fluid surface

Correct answer: (D)
Be fully immersed with top surface at fluid surface

39. A model of torpedo is tested in a towing tank at a velocity of 25 m/sec. The prototype is expected to attain a velocity of 5 m/sec. What model scale has been used?

  1. 1 : 5
  2. 1 : 2.5
  3. 1 : 25
  4. 1:√5

Correct answer: (A)
1 : 5

40. A moving fluid mass may be brought to a static equilibrium position, by applying an imaginary inertia force of the same magnitude as that of the accelerating force but in the opposite direction. This statement is called

  1. Pascal's law
  2. Archimedes's principle
  3. D-Alembert's principle
  4. None of these

Correct answer: (C)
D-Alembert's principle

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