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JEE Main
Exam
JEE Main
Subject
Physics
Chapter
Mechanical Properties of Solids

JEE Main · Physics · Mechanical Properties of Solids

A wire has a breaking stress of 6 × 10 ^ 5 Nm^ - 2 ~and a density...

A wire has a breaking stress of 6×105Nm−26 \times {10}^{5}Nm^{- 2}~and a density of~3×104kgm−33 \times {10}^{4}kgm^{- 3}. The length of the wire of the same material~will break under its own weight if g=10ms−2g = 10ms^{- 2}& is

Options

  1. A2m2m
  2. B20m20m
  3. C200m200m
  4. D2000m2000m

Correct answer

A. 2m2m

Step-by-step solution

Given: Breaking stress& =6×105Nm−2= 6 \times {10}^{5}Nm^{- 2}.

Density~ρ=3×104kgm−3ρ = 3 \times {10}^{4}kgm^{- 3}.

Stress is the ratio of force acting on a unit area of an object given as~Stress=FAStress = \dfrac{F}{A}.

We~know that force is given as~F=F =mass ×\timesacceleration.

Thus, breaking stress~=mgA= \dfrac{mg}{A}.

Since, density is stated as~=massvolume= \dfrac{mass}{volume}, so~m=ρV=ρALm = ρV = ρAL.

Putting in stress formula, we get~Stress=ρALgA=ρLgStress = \dfrac{ρALg}{A} = ρLg

6×105=3×104×L×10⇒L=2m6 \times {10}^{5} = 3 \times {10}^{4} \times L \times 10⇒ L = 2m

Hence, the length of the wire is~2m2m.

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