Q: The length of the wire OE is divided into five equal parts OA, AB, BC, CD and DE. The wire is made to hang from E and its length is , $ \displaystyle \frac{5 \sigma_b }{4 \rho g}$ where σb is the breaking stress and ρ is the density of the material of the wire. The point at which wire will break, is
(a) A
(b) B
(c) C
(d) D
Click to See Answer :
Ans: (d)
Sol: Breaking Stress = Breaking force / Area = Weight/Area
σb = ALρg/A
L = σb/ρg
Length of wire = 5σb/4ρg
From O to D ,
Length = 4σb/4ρg = σ/ρg
Hence wire will break at point D