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NEET Sample Paper NEET Sample Test Paper-53

  • question_answer
    A spring has a length \[{{l}_{1}}\] when tension in it is\[{{n}_{1}}\left( in\text{ }N \right)\]. It has a length \[{{l}_{2}}\] when tension is\[{{n}_{2}}\left( in\,N \right)\]. Find its spring constant-

    A) \[\frac{({{n}_{2}}{{l}_{2}}-{{n}_{1}}{{l}_{1}})}{({{l}_{1}}-{{l}_{2}})}\]                 

    B) \[\frac{({{n}_{1}}-{{n}_{2}})}{({{l}_{1}}-{{l}_{2}})}\]

    C) \[\frac{({{n}_{2}}-{{n}_{1}})}{({{l}_{1}}-{{l}_{2}})}\]                       

    D) \[\frac{({{n}_{1}}{{l}_{1}}-{{n}_{2}}{{l}_{2}})}{({{l}_{1}}-{{l}_{2}})}\]  

    Correct Answer: B

    Solution :

    let string constant K & natural length \[\ell \] \[So\,\,{{n}_{1}}=\,\,K({{\ell }_{1}}-\ell )\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,.....(i)\] \[{{n}_{2}}=\,\,K({{\ell }_{2}}-\ell )\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,.....(ii)\] By solving \[K=\frac{{{n}_{1}}+{{n}_{2}}}{{{\ell }_{1}}-{{\ell }_{2}}}\]


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