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Properties of Matter

Elasticity, viscosity, surface tension, fluid pressure

Key Concepts
  • Young's modulus (Y): resistance to longitudinal strain
  • Bulk modulus (B): resistance to volume change
  • Modulus of rigidity (η): resistance to shear strain
  • Surface tension: tendency of liquid surface to contract
  • Bernoulli's principle: pressure + KE/vol + PE/vol = constant
Important Formulae
Young's modulus Y = (F/A) / (ΔL/L)
Hydrostatic pressure P = hρg
Bernoulli's equation P + ½ρv² + ρgh = constant
Stokes' law (viscous drag) F = 6πηrv
Terminal velocity v_t = 2r²(ρ − σ)g / 9η
Excess pressure in bubble ΔP = 4T/r (soap bubble), 2T/r (liquid drop)
Quick Tips
  • Continuity equation: A₁v₁ = A₂v₂ (incompressible fluid).
  • Capillary rise h = 2T cosθ / (rρg); rises in narrow tubes, falls for mercury.
  • Poisson's ratio σ = lateral strain / longitudinal strain; always between 0 and 0.5.
Sample Practice Questions

  1. Surface tension of a liquid is defined as force per unit:

    • Area
    • Length
    • Volume
    • Mass
    Show answer

    Answer: Length

  2. Terminal velocity of a sphere of radius r in fluid of viscosity η and density ρf (sphere density ρ):

    • r²(ρ−ρf)g/9η
    • 2r²(ρ−ρf)g/9η
    • 2r(ρ−ρf)g/9η
    • 2r²ρg/9η
    Show answer

    Answer: 2r²(ρ−ρf)g/9η

  3. The excess pressure inside a soap bubble of radius r and surface tension T:

    • T/r
    • 2T/r
    • 4T/r
    • 8T/r
    Show answer

    Answer: 4T/r

  4. When water rises in a capillary, the surface is:

    • Convex
    • Concave
    • Flat
    • Irregular
    Show answer

    Answer: Concave

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Practice Questions

Practice 20 randomly selected NEET questions on Properties of Matter. Answers are revealed after each question.

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