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

  • question_answer
    A weight w is to be moved from the bottom to the top of an inclined plane of inclination 9 to the horizontal. If a smaller force is to be applied to drag it along the plane in comparison to lift it vertically up, the coefficient of friction should be such that:

    A) \[\mu >\tan \left( \frac{\pi }{4}-\frac{\theta }{2} \right)\]   

    B) \[\mu <\tan \left( \frac{\pi }{4}-\frac{\theta }{2} \right)\]

    C) \[\mu <\tan \theta \]                  

    D) \[\mu >\tan \frac{\pi }{4}\]

    Correct Answer: B

    Solution :

    \[{{F}_{1}}=w\sin \theta +\mu w\cos \theta \]
    As,    \[{{F}_{1}}<{{F}_{2}}\]
    \[\therefore \,\,\mu <\tan \left( \frac{\pi }{4}=\frac{\theta }{2} \right)\]

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