Buoyancy and Floatation MCQ – Fluid Mechanics

1. Centre of buoyancy is

  1. the point through which the submerged weight of the body acts
  2. the point thoroughly which the buoyant force acts
  3. the point through which the resultant hydrostatic force acts
  4. the centre of gravity of the liquid displaced by the body
Answer
Answer. b

2. Centre of buoyancy always

  1. coincides with the centre of gravity
  2. coincides with the centroid of the volume of fluid displaced
  3. remains above the centre of gravity
  4. remains below the centre of gravity
Answer
Answer. b

3. The buoyancy depends upon the

  1. weight of the liquid displaced
  2. pressure with which the liquid is displaced
  3. viscosity of the liquid
  4. compressibility of the liquid
Answer
Answer. a

4. A floating body attains stable equilibrium if its metacentre is

  1. at the centroid
  2. above the centroid
  3. below the centroid
  4. anywhere
Answer
Answer. b

5. For a submerged body, if the centre of buoyancy is above the centre of gravity, the equilibrium is called as

  1. stable equilibrium
  2. unstable equilibrium
  3. neutral equilibrium
  4. restoring equilibrium
Answer
Answer. a

6. The point about which a floating body starts oscillating when the body is tilted is called

  1. centre of buoyancy
  2. centre of gravity
  3. centre of pressure
  4. metacentre
Answer
Answer. d

7. The magnitude of the buoyant force can be determined by

  1. Newton’s Law of viscosity
  2. Principle of moments
  3. Archimedes principle
  4. Bernoulli’s principle
Answer
Answer. c

8. Buoyant unit weight equals the saturated density

  1. multiplied by unit weight of water
  2. divided by unit weight of water
  3. plus unit weight of water
  4. minus unit weight of water
Answer
Answer. d

9. The centre of buoyancy is

  1. point of intersection of the buoyant force and the centerline of the body
  2. point of intersection of the buoyant force and the gravitational force
  3. centre of gravity of the body
  4. centre of the displaced fluid volume
Answer
Answer. d

10. The centre of gravity of the volume of the liquid displaced is called

  1. Centre of buoyancy
  2. Metacentre
  3. Centre of pressure
  4. None of the above
Answer
Answer. a

11. A solid body sinks in a fluid when

  1. the specific gravity of its material is greater than unity
  2. the buoyancy force does not pass through the metacentre
  3. the weight of the fluid displaced is less than the weight of the body
  4. the metacentre lies below the Centre of gravity
Answer
Answer. c

12. When metacentre of a floating body is lower than that the center of gravity, then the body will be in

  1. unstable equilibrium
  2. stable equilibrium
  3. neutral equilibrium
  4. any of the above depending on other factors
Answer
Answer. a

13. A floating body is said to be unstable if the metacentre (M) is

  1. equal to the centre of mass of the body
  2. above the centre of mass of the body
  3. below the centre of mass of the body
  4. outside the body
Answer
Answer. c

14. The moment of inertia of a floating body along its longitudinal axis and the volume of water displaced by it are I and V respectively. The height of the metacentre above centre of buoyancy of the body, is

  1. I/2V
  2. 2I/V
  3. I/V
  4. 3I/V
Answer
Answer. c

15. If the position of metacentre remain lower than centre of gravity of the floating body, the body will remain in a state of

  1. stable equilibrium
  2. unstable equilibrium
  3. neutral equilibrium
  4. none of the above
Answer
Answer. b

16. A floating body is said to be in a state of stable equilibrium

  1. when its metacentric height is zero
  2. when the metacentre is above the centre of gravity
  3. when the metacentre is below the centre of gravity
  4. only when its centre of gravity is below its centre of buoyancy
Answer
Answer. b

17. For a submerged body, if the centre of buoyancy coincides with the centre of gravity, the equilibrium is called

  1. unstable
  2. stable
  3. neutral
  4. none of the above
Answer
Answer. c

18. A body floating in a liquid is said to be in neutral equilibrium if its metacentre

  1. coincides with its centre of gravity
  2. lies above its centre of gravity
  3. lies below its centre of gravity
  4. lies below the centre of buoyancy and centre of gravity
Answer
Answer. a

19. The body will float if the force of buoyancy is _________ the weight of the liquid displaced.

  1. equal to
  2. less than
  3. more than
  4. equal and less than to
  5. none of these options
Answer
Answer. c

20. When a body floating in a liquid is given a small angular displacement, it stands oscillating about a point known as

  1. centre of pressure
  2. centre of gravity
  3. centre of buoyancy
  4. metacentre
Answer
Answer. d
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