Question

Why is always pressure calculated on perpendicular force, why not tangential force?

Answer 1

Dear Student,

Pressure is calculated on perpendicular force, and not tangential force because tangential component of a force doesn't "press" the surface. It just grazes the surface. Normal component "presses" the surface.
Hence, by definition itself, pressure is given as force per unit normal area and not force per unit area.

Regards