Physics · MECHANICAL PROPERTIES OF FLUIDS

A static fluid differs fundamentally from a solid in its response to external mechanical stresses. When a tangential (shear) stress is applied to a fluid at rest, the fluid:

1. A
   sustains the shear stress via bulk modulus, maintaining zero displacement gradient.
2. B
   develops a static shear strain directly proportional to the applied shear stress, remaining in static equilibrium.
3. C
   undergoes a reversible volumetric change without altering its boundary shape.
4. D
   cannot sustain any static shear stress, however small, and begins to flow continuously.