JEE Main & Advanced Physics Simple Harmonic Motion Question Bank Critical Thinking

  • question_answer
    A particle is performing simple harmonic motion along x-axis with amplitude 4 cm and time period 1.2 sec. The minimum time taken by the particle to move from x =2 cm to x = + 4 cm  and back again is given by               [AIIMS 1995]

    A)            0.6 sec                                     

    B)            0.4 sec

    C)            0.3 sec                                     

    D)            0.2 sec

    Correct Answer: B

    Solution :

                       Time taken by particle to move from x=0 (mean position) to x = 4 (extreme position)\[=\frac{T}{4}=\frac{1.2}{4}=0.3\ s\]                    Let t be the time taken by the particle to move from x=0 to x=2 cm                    \[y=a\sin \omega t\Rightarrow 2=4\sin \frac{2\pi }{T}t\]\[\Rightarrow \frac{1}{2}=\sin \frac{2\pi }{1.2}t\]                    \[\Rightarrow \frac{\pi }{6}=\frac{2\pi }{1.2}t\Rightarrow t=0.1\ s\]. Hence time to move from x = 2 to x = 4 will be equal to 0.3 ? 0.1 = 0.2 s            Hence total time to move from x = 2 to x = 4 and back again \[=2\times 0.2=0.4\sec \]


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