J & K CET Engineering J and K - CET Engineering Solved Paper-2010

  • question_answer
    The equation of a damped simple harmonic motion is \[m\frac{{{d}^{2}}x}{d{{t}^{2}}}+\frac{dx}{dt}+kx=0\]. Then the angular frequency of oscillation is

    A)  \[\omega ={{\left( \frac{k}{m}-\frac{{{b}^{2}}}{4{{m}^{2}}} \right)}^{1/2}}\]

    B)  \[\omega ={{\left( \frac{k}{m}-\frac{b}{4m} \right)}^{1/2}}\]

    C)  \[\omega ={{\left( \frac{k}{m}-\frac{{{b}^{2}}}{4m} \right)}^{1/2}}\]

    D)  \[\omega ={{\left( \frac{k}{m}-\frac{{{b}^{2}}}{4{{m}^{2}}} \right)}^{1/2}}\]

    Correct Answer: A

    Solution :

    Displacement of damped oscillator is given by \[x={{x}_{m}}{{e}^{-bt/2m}}\sin (\omega 't+\phi )\] where \[\omega '=\]angular frequency of damped oscillator \[=\sqrt{\omega _{0}^{2}-{{(b/2m)}^{2}}}\] \[=\sqrt{\frac{k}{m}-\frac{{{b}^{2}}}{4{{m}^{2}}}}\]


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