Chirkut.বাংলা

MCQ practice · SSC Physics Board questions · Chapter 5: State of Matter and Pressure

Dhaka Board 2022

Buoyancy is-

  1. i. the weight of the fluid displaced by the body
  2. ii. the resultant upward force
  3. iii. Vρg

Think it through first, then pick an option.

  1. a i and ii
  2. b i and iii
  3. c ii and iii
  4. d i, ii and iii
Answer and explanation

Correct answer: d i, ii and iii

i is true: by Archimedes' principle the buoyancy equals the weight of the displaced liquid.; ii is true: the upward force on the lower face is larger, so the resultant is upward; it is called buoyancy.; iii is true: the displaced liquid has volume V and density ρ, so its weight is Vρg.

Why the other options are wrong

  • a i and ii: Statement iii is true but this option leaves it out: the displaced liquid has volume V and density ρ, so its weight is Vρg.
  • b i and iii: Statement ii is true but this option leaves it out: the upward force on the lower face is larger, so the resultant is upward; it is called buoyancy.
  • c ii and iii: Statement i is true but this option leaves it out: by Archimedes' principle the buoyancy equals the weight of the displaced liquid.