Chapter 1 : Introduction and Fundamental Concepts
Lecture 1 :

 
Distinction Between Solid and Fluid

Solid
Fluid

  • More Compact Structure

  • Attractive Forces between the molecules
    are larger therefore more closely packed

  • Solids can resist tangential stresses in static condition

  • Whenever a solid is subjected to shear stress
    1. It undergoes a definite deformation α or breaks
    2. α is proportional to shear stress upto some limiting condition

  • Solid may regain partly or fully its original shape when the tangential stress is removed


  • Less Compact Structure

  • Attractive Forces between the molecules
    are smaller therefore more loosely packed

  • Fluids cannot resist tangential stresses in static condition.

  • Whenever a fluid is subjected to shear stress
    1. No fixed deformation
    2. Continious deformation takes place
      until the shear stress is applied

  • A fluid can never regain its original shape, once it has been distorded by the shear stress

 

Fig 1.3 Deformation of a Solid Body