AIIMS AIIMS Solved Paper-2007

  • question_answer
    A mass of 2.0 kg is put on a flat    pan attached to a vertical spring fixed on the ground as shown in the figure. The mass of the spring and the pan is negligible. When pressed slightly and released the mass executes a simple harmonic motion. The spring constant is 200 N/m. What should be the minimum amplitude of the motion, so that the mass gets detached from the pan?(Take \[g=10\,m/{{s}^{2}}\])

    A)  8.0 cm

    B)  10.0cm

    C)  Any value less than 12.0 cm

    D)  4.0cm

    Correct Answer: B

    Solution :

    Let the minimum amplitude of SHM is a. Restoring force on spring \[v_{f}^{2}=v_{i}^{2}+\frac{2G{{m}_{e}}}{{{R}_{e}}}\left( 1+\frac{1}{10} \right)\] Restoring force is balanced by weight mg of block. For mass to execute simple harmonic motion of amplitude a. \[v_{f}^{2}=v_{i}^{2}+\frac{2G{{m}_{e}}}{{{R}_{e}}}\left( 1-\frac{1}{10} \right)\]   \[v_{f}^{2}=v_{i}^{2}+\frac{2Gm}{{{R}_{e}}}\left( 1-\frac{1}{10} \right)\] or   \[\mathbf{\vec{v}}\] Here, \[\mathbf{\vec{B}}\] \[{{i}_{2}}>{{i}_{3}}>{{i}_{1}}\]     \[{{i}_{2}}>{{i}_{1}}>{{i}_{3}}\] \[{{i}_{1}}>{{i}_{2}}>{{i}_{3}}\] Hence, minimum amplitude of the motion should be 10 cm, so that the mass gets detached from the pan.


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