Question

A substance breaks down by a stress of (10^6 N)/m^2. If the density of the material of the wire is 3×(10^3) kg/m^3, then the length of the wire of the substance which will break under its own weight when suspended vertically will be ___________

(a) 66.6m

(b) 60.0m

(c) 33.3m

(d) 30.3m

The question was posed to me in a job interview.

My doubt stems from Elastic Limit in section Thermal Properties of Matter of Engineering Physics I

Answer 1

Right option is (c) 33.3m

The best I can explain: Breaking stress = mg/area=Alρg/A=lρg

l=Stress/ρg=10^6/(3×10^3×10)=33.3m.