Question

Define Factor of safety

(a) Ultimate stress/Permissible stress

(b) Ultimate stress/ Shear stress

(c) Compressive stress/ Ultimate stress

(d) Tensile stress/Shear stress

The question was posed to me in an international level competition.

My doubt stems from Shear Stress and Pressure Gradient topic in section Viscous Flow & Turbulent Flow of Fluid Mechanics

Answer 1

The correct choice is (a) Ultimate stress/Permissible stress

For explanation I would say: Factor of safety determines the maximum load carrying capacity. It tells us how much stronger the system is than it usually needs to be for a particular specified load. It is the ratio of allowable stress to the actual stress.