Answer: 800 kg m-3.
- A 600 kg m-3
- B 900 kg m-3
- C 800 kg m-3
- D 1250 kg m-3
Correct answer: C. 800 kg m-3
Explanation: Fraction submerged = ρblock/ρwater, so ρ = 0.8 × 1000 = 800 kg m-3.
Since the same volume of fluid must pass every cross-section per second (continuity), the fluid speeds up where the pipe narrows; Bernoulli's equation then says this faster-moving fluid has lower pressure - the principle behind a venturi meter and an aircraft wing's lift.
Concept context
Pressure, buoyancy, Bernoulli equation, viscosity, and surface tension.