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

  • question_answer
    A load W produces an extension of 1mm in a thread of radius r. Now if the load is made 4W and radius is made 2r all other things remaining same, the extension will become                         [RPET 2000]

    A) 4 mm  

    B)             16 mm

    C)             1 mm  

    D)             0.25 mm

    Correct Answer: C

    Solution :

                    \[l=\frac{FL}{AY}\therefore l\propto \frac{F}{{{r}^{2}}}\]             \[\frac{{{l}_{1}}}{{{l}_{2}}}=\frac{{{F}_{2}}}{{{F}_{1}}}{{\left( \frac{{{r}_{1}}}{{{r}_{2}}} \right)}^{2}}=(4)\times {{\left( \frac{1}{2} \right)}^{2}}=1\]\\[{{l}_{2}}={{l}_{1}}=1mm\]


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