JEE Main & Advanced Physics Simple Harmonic Motion Question Bank Superposition of S H M and Resonance

  • question_answer
    The resultant of two rectangular simple harmonic motions of the same frequency and unequal amplitudes but differing in phase by \[\frac{\pi }{2}\] is [BHU 2003; CPMT 2004; MP PMT 1989, 2005; BCECE 2005]

    A)            Simple harmonic                

    B)            Circular

    C)            Elliptical                                  

    D)            Parabolic

    Correct Answer: C

    Solution :

                       If first equation is \[{{y}_{1}}={{a}_{1}}\sin \omega \,t\]Þ \[\sin \omega \,t=\frac{{{y}_{1}}}{{{a}_{1}}}\]  ... (i) then second equation will be \[{{y}_{2}}={{a}_{2}}\sin \left( \omega \,t+\frac{\pi }{2} \right)\] \[={{a}_{2}}\,\left[ \sin \omega \,t\cos \frac{\pi }{2}+\cos \omega \,t\sin \frac{\pi }{2} \right]={{a}_{2}}\cos \omega \,t\] Þ \[\cos \omega \,t=\frac{{{y}_{2}}}{{{a}_{2}}}\]                                       ... (ii) By squaring and adding equation (i) and (ii)      \[{{\sin }^{2}}\omega \,t+{{\cos }^{2}}\omega \,t=\frac{y_{1}^{2}}{a_{1}^{2}}+\frac{y_{2}^{2}}{a_{2}^{2}}\] Þ  \[\frac{y_{1}^{2}}{a_{1}^{2}}+\frac{y_{2}^{2}}{a_{2}^{2}}=1\]; This is the equation of ellipse.


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