VMMC VMMC Medical Solved Paper-2007

  • question_answer
    The tension in vibrating streched piano wire is 10 N. To double the frequency, the tension in wire must be

    A) 5 N        

    B)                        20 N                      

    C) 40 N                      

    D)        80 N

    Correct Answer: C

    Solution :

    The fundamental frequency (n) of a wire of length I and tension T is given by \[n=\frac{1}{2l}\sqrt{\frac{T}{m}},\] where m is mass per unit length of wire. Given,  \[{{n}_{1}}=n,{{T}_{1}}=T,{{n}_{2}}=2n\] \[\therefore \]  \[\frac{{{n}_{1}}}{{{n}_{2}}}=\sqrt{\frac{{{T}_{1}}}{{{T}_{2}}}}\] \[{{T}_{2}}={{\left( \frac{{{n}_{2}}}{{{n}_{1}}} \right)}^{2}}{{T}_{1}}\]                 \[\therefore \]  \[{{T}_{2}}={{(2)}^{2}}\times 10=40N\]


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