JEE Main & Advanced Physics Work, Energy, Power & Collision / कार्य, ऊर्जा और शक्ति Question Bank Self Evaluation Test - Work, Energy and Power

  • question_answer
    A 1 kg particle at a height of 8m has a speed of 1 Om/s down a fixed incline making an angle \[53{}^\circ \] with horizontal as shown in figure. It slides on a horizontal section of length 10 m at ground level and then up a fixed incline making an angle \[37{}^\circ \] with horizontal. All surfaces have\[{{\mu }_{k}} = 0.5\]. How far (in meters) from point 0 (bottom of right inclined plane), along the incline making an angle \[37{}^\circ \] with horizontal, does the particle first come to rest?       

    A) 1m

    B) 0.5m

    C) 2m

    D) 5m

    Correct Answer: A

    Solution :

    [a] Let x be the distance travelled by the particle along the \[37{}^\circ \] incline, after which it comes to rest. From work-energy theorem. Work done by gravity on block on incline \[53{}^\circ +\] work done by friction on block on incline \[53{}^\circ =\] work done by friction on ground level + work done by gravity on block on incline \[37{}^\circ +\] work done by friction on block on incline \[37{}^\circ =\] change in K.E. \[\operatorname{mg}\left( 8 \right)-\mu mg cos 53{}^\circ \left( 10 \right) - umg\left( 10 \right)-\mu mg cos\]\[37{}^\circ \left( x \right)\] \[-mg sin 37{}^\circ  \left( x \right) = 0-\frac{1}{2}\left( 1 \right) {{\left( 10 \right)}^{2}}\] On solving we get \[x=1\text{ }m\]


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