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

  • question_answer
    A block of mass m is placed over a plank of mass M, which is placed over a smooth horizontal surface as shown in the figure. Friction exists between the block and plank. A horizontal force (which increases with time according to law\[F=\alpha t\]) is applied horizontally on the plank. Then which of the following graphs shows acceleration a of the block?





    Correct Answer: A

    Solution :

    [a] First increasing state friction acts \[{{f}_{s}}=m.a=\frac{m\times F}{m+M}\Rightarrow a=\frac{\alpha t}{m+M}\] then \[{{f}_{K}}=\mu mg=ma\] \[a=\mu g\]

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