JEE Main & Advanced Physics Wave Mechanics Question Bank Self Evaluation Test - Oscillations

  • question_answer
    A simple harmonic oscillator of angular frequency \[2\,rad\,{{s}^{-1}}\] is acted upon by an external force F = sin t N. If the oscillator is at rest in its equilibrium position at t = 0, its position at later times is given by:            

    A) \[\sin \,t+\frac{1}{2}\cos \,2t\]

    B) \[\cos t-\frac{1}{2}\sin \,2t\]

    C) \[\sin t-\frac{1}{2}\sin \,2t\]

    D) \[\sin t+\frac{1}{2}\sin \,2t\]

    Correct Answer: C

    Solution :

    [c] As we know, \[F=ma\Rightarrow a\propto F\,\,or,\,a\propto \,\,\sin \,t\] \[\Rightarrow \frac{dv}{dt}\propto \sin t\Rightarrow \int\limits_{0}^{0}{dV\propto \int\limits_{0}^{t}{\sin t\,dt}}\] \[V\propto -\cos \,t+1\] \[\int\limits_{0}^{x}{dx}=\int\limits_{0}^{t}{(-\cos t+1)dt}\] \[x=\sin \,t-\frac{1}{2}\sin 2t\]


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