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⚛️ Physics  ·  Mechanical Properties of Fluids  ·  NEET & JEE

An object of density ρ = 0.6 g/cm³ floats in water. The fraction of its volume above water is:

Answer: 0.4 (40%).

  • A 0.4 (40%)
  • B 0.6 (60%)
  • C 0.5 (50%)
  • D 0.1 (10%)

Correct answer: A. 0.4 (40%)

Explanation: For floating: ρ_object / ρ_water = V<sub>submerged</sub> / V<sub>total</sub>. 0.6/1.0 = V<sub>sub</sub>/V = 0.6. Fraction submerged = 60%. Fraction above = 40%.

Continuity Equation: Narrow Pipe → Faster FlowA₁, v₁ (wide, slow)A₂, v₂ (narrow, fast)A₁v₁ = A₂v₂ (continuity)Smaller area → higher speed → (by Bernoulli) LOWER pressure

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.

Read the full Mechanical Properties of Fluids notes →