JEE Main & Advanced Physics NLM, Friction, Circular Motion Sample Paper Topic Test - Friction

  • question_answer
    A heavy uniform chain lies on horizontal table top. If the coefficient of friction between the chain and the table surface is 0.25 then the maximum fraction of length of chain that can hang over on edge of table is

    A) 20%   

    B) 35%   

    C) 25%                             

    D) 15%

    Correct Answer: A

    Solution :

    Force of Friction on chain = weight of hanging chain.
    \[\mu (1-x)\rho g=x\rho g\] or \[\mu \,(l-x)=x;\]
    \[\mu \,\ell =\,(\mu +1)x\] or \[x=\mu \ell \,(1+\mu )\].
    \[x=\frac{.25\ell }{.25+1}=.\frac{.25\ell }{1.25}=.2\ell \Rightarrow \,\frac{x}{\ell }=.2=20%\]

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