BCECE Medical BCECE Medical Solved Papers-2015

  • question_answer
    If two simple pendulums first of bob mass \[{{M}_{1}}\]and length \[{{l}_{1}}\] second of bob mass \[{{M}_{2}}\] and length \[{{l}_{2}}\]. Given \[{{M}_{1}}={{M}_{2}}\] and \[{{l}_{1}}=2{{l}_{2}}\]. If the vibrational energies of both are same, then which of the following is correct?

    A)  Amplitude of B is smaller than A

    B)  Amplitude of B is greater than B

    C)  Amplitude will be same

    D)  None of the above

    Correct Answer: A

    Solution :

    Frequency, \[n=\frac{1}{2\pi }\sqrt{\frac{g}{l}}\] or            \[n\propto \frac{1}{\sqrt{l}}\] \[\therefore \] \[\frac{{{n}_{1}}}{{{n}_{2}}}=\sqrt{\frac{{{l}_{2}}}{{{l}_{1}}}}=\sqrt{\frac{{{l}_{2}}}{2{{l}_{2}}}}\]                 \[\frac{{{n}_{1}}}{{{n}_{2}}}=\frac{1}{\sqrt{2}}\] \[\Rightarrow \] \[{{n}_{2}}=\sqrt{2{{n}_{1}}}\] \[\Rightarrow \] \[{{n}_{2}}>{{n}_{1}}\] Energy, \[E=\frac{1}{2}m{{\omega }^{2}}{{a}^{2}}\] and         \[{{a}^{2}}\propto \frac{1}{m{{n}^{2}}}\] {\[\because \] E is same} \[\therefore \] \[\frac{a_{1}^{2}}{a_{2}^{2}}=\frac{{{m}_{2}}n_{2}^{2}}{{{m}_{1}}n_{1}^{2}}\] Given, \[{{n}_{2}}>{{n}_{1}}\] and \[{{m}_{1}}>{{m}_{2}}\] \[\Rightarrow \] \[{{a}_{1}}>{{a}_{2}}\]. So, amplitude of B is smaller than A,


You need to login to perform this action.
You will be redirected in 3 sec spinner