JEE Main & Advanced Physics Elasticity Question Bank Youngs Modulus and Breaking Stress

  • question_answer
    Two similar wires under the same load yield elongation of 0.1 mm and 0.05 mm respectively. If the area of cross- section of the first wire is \[4m{{m}^{2}},\] then the area of cross section of the second wire is      [CPMT 2000; Pb. PET 2002]

    A)             \[6m{{m}^{2}}\]     

    B)             \[8m{{m}^{2}}\]

    C)             \[10\,m{{m}^{2}}\]

    D)                      \[12\,m{{m}^{2}}\]

    Correct Answer: B

    Solution :

                    \[l=\frac{FL}{AY}\therefore l\propto \frac{1}{A}\]   (F,L and Y are constant)             \[\frac{{{A}_{2}}}{{{A}_{1}}}=\frac{{{l}_{1}}}{{{l}_{2}}}\Rightarrow {{A}_{2}}={{A}_{1}}\left( \frac{0.1}{0.05} \right)\]= \[2{{A}_{1}}=2\times 4=8m{{m}^{2}}\]


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