Question

A static fluid can have positive normal stress and zero shear stress

Answer 1

For a static fluid, the shear stress is zero and the onlystress is the normal stress, i.e., pressure p. Recall that p is a scalar, which when in contact with a solid surface exerts a normal force towards the surface.

Answer 2

Static fluid:

• A static fluid can have zero shear stress and normal positive pressure.

• For a static fluid, the only stress is the normal stress since a fluid subjected to a shear stress must deform and experience motion.  

• Shear stress will only exists when the fluid flows. But any fluid will exert pressure equally in all directions, so it will be having positive normal stress.

Hope it helped....