DUMET Medical DUMET Medical Solved Paper-2007

  • question_answer
    If \[{{k}_{s}}\] and \[{{k}_{p}}\] respectively are effective spring constant in series and parallel combination of of springs as shown in figure, find \[\frac{{{k}_{s}}}{{{k}_{p}}.}\]

    A)  \[\frac{9}{2}\]             

    B)  \[\frac{3}{7}\]

    C)  \[\frac{2}{9}\]                

    D)  \[\frac{7}{3}\]  

    Correct Answer: C

    Solution :

     In the arrangement shown in figure (I) the two springs are in series. The effective spring constant k, of this arrangement is \[\frac{1}{{{k}_{S}}}=\frac{1}{k}+\frac{1}{2k}\] or \[\frac{1}{{{k}_{S}}}=\frac{2+1}{2k}=\frac{3}{2k}\] \[\therefore \] \[{{k}_{S}}=\frac{2k}{3}\] In the arrangement shown in figure (II) the two springs are in parallel. The effective spring constant \[{{k}_{p}}\] of this arrangement is \[{{k}_{p}}={{k}_{1}}+{{k}_{2}}\] \[=k+2k=3k\] \[\therefore \] \[\frac{{{k}_{S}}}{{{k}_{P}}}=\frac{2k/3}{3k}=\frac{2}{9}\]


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