Buoyancy and Floatation MCQ – Fluid Mechanics

31. The condition of stable equilibrium for a floating body is

  1. the metacentre M coincides with the centre of gravity G
  2. the metacentre M is above centre of gravity G
  3. the metacentre M is below centre of gravity G
  4. the centre of buoyancy B is above centre of gravity G
Answer
Answer. b

32. A body in neutral equilibrium will rotate about the

  1. centre of gravity and meta centre
  2. centre of pressure and meta centre
  3. centre of gravity and centre of buoyancy
  4. centre or gravity and centre of buoyancy and meta centre
Answer
Answer. b

33. Which one of the following statements indicates equilibrium of fully submerged bodies?

  1. Centre of buoyancy should be below centre of gravity
  2. Centre of gravity should be below metacentre
  3. Centre of gravity should be above metacentre
  4. Centre of buoyancy should be above centre of gravity
Answer
Answer. a

34. An ocean liner, 240 m long and 24 m wide, displaces 654 MN of sea-water (ρ = 1025 kgf/m3). The second moment of inertia of the water plane about its fore-aft axis is 2/3 of that of the circumscribing rectangle. The position of the centre of buoyancy is 2.30 m below the centre of gravity. How high is the metacentre above the centre of buoyancy (to the nearest cm)?

  1. 53 cm
  2. 49 cm
  3. 65 cm
  4. 58 cm
Answer
Answer. a

35. When a block of ice floating on water in a container melts, the level of water in the container

  1. rises
  2. first falls and then rises
  3. remains the same
  4. falls
  5. first rises and then falls
Answer
Answer. c

36. A square wooden (SG = 0.6) rod, 5 cm by 5 cm by 10 cm long, floats vertically in water at 20°C when 6 kg of steel (SG = 7.84) are attached to the lower end. How high above the water surface does the wooden end of the rod protrude?

  1. 1.6 m
  2. 0.6 m
  3. 1.9 m
  4. 2.4 m
Answer
Answer. c

37. Principle involved in the relationship between submerged unit weight and saturated weight of a soil is based on

  1. Equilibrium of floating bodies
  2. Archimedes’ principle
  3. Stokes’ law
  4. Darcy’s law
Answer
Answer. b

38. A cubical block of 1 m side length floats in water, the depth of immersion being 0,4m. If the specific gravity of water is 1.0, then the mass of the block is

  1. 40 kg
  2. 100 kg
  3. 400 kg
  4. 1000 kg
Answer
Answer. c

39. The vertical component of the hydrostatic force on a submerged curve surface is

  1. the mass of the liquid vertically above it
  2. the weight of the liquid vertically above it
  3. the force on a vertical projection of the surface
  4. the product of the pressure at centroid and the surface area
Answer
Answer. b

40. A body weighing 40 N is losing 5 N weight when submerged in water. Then its specific gravity of the body is equal to

  1. 8
  2. 6
  3. 2
  4. 4
Answer
Answer. a
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