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⚛️ Physics  ·  Mechanical Properties of Fluids  ·  NEET & JEE

The velocity of efflux from a tank depends only on the depth of the hole below the water surface (not tank dimensions). This is called:

Answer: Torricelli's theorem.

  • A Torricelli's theorem
  • B Bernoulli's principle
  • C Pascal's law
  • D Archimedes' principle

Correct answer: A. Torricelli's theorem

Explanation: Torricelli's theorem: v = √(2gh). The efflux velocity is determined solely by the depth h of the hole below the free surface, regardless of tank shape or size.

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 →