JEE Main & Advanced Sample Paper JEE Main - Mock Test - 16

  • question_answer
    A block of mass M is placed on top of a hole in a horizontal table. A spring of force constant k is connected to the block through the hole. The other end of the massless spring has a particle of mass m connected to it. With what maximum amplitude can the particle oscillate up and down such that the block does not lose contact with the table?

    A)         \[\frac{Mg}{2k}+\frac{mg}{k}\] 

    B)        \[\frac{2Mg}{k}+\frac{mg}{2k}\]

    C) \[\frac{Mg}{k}+\frac{2mg}{k}\] 

    D)        \[\frac{Mg}{k}+\frac{mg}{k}\]

    Correct Answer: D

    Solution :

    [d] The block will lose contact if the spring compresses more than \[\frac{Mg}{k}\]. In equilibrium position the spring is stretched by \[\frac{mg}{k}\] . If the spring oscillates with amplitude A, it will move up above its equilibrium position by A. It means compression in this extreme win position will be \[A-\frac{mg}{k}\]. For the block to remain on the table, \[A-\frac{Mg}{k}=\frac{mg}{k}\] \[A=\frac{Mg}{k}+\frac{mg}{k}\]


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