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JEE Main & Advanced Physics Work, Energy, Power & Collision / कार्य, ऊर्जा और शक्ति JEE PYQ - Work Energy Power and Collision

  • question_answer
    A particle which is experiencing a force, given by \[\overrightarrow{F}=3\overrightarrow{i}-12\overrightarrow{j}\], undergoes a displacement of \[\overrightarrow{d}=4\overrightarrow{i}\] . If particle had a kinetic energy of 3 J at the beginning of the displacement what is its kinetic energy at the end of the displacement? [JEE Main 10-Jan-2019 Evening]

    A) 9 J

    B) 10 J

    C) 12 J

    D) 15 J

    Correct Answer: D

    Solution :

    [d] \[w=\overrightarrow{F}.\overrightarrow{d}=(3\,\widehat{i}-12\,\widehat{j}).\left( 4\,\widehat{i} \right)\]
    \[w=12\] Joule
    W.E.T.
    \[{{w}_{Total}}=\Delta \,k={{k}_{f}}-{{k}_{i}}\]
    \[12={{k}_{f}}-3J\]
    \[\Rightarrow \,\,\,{{k}_{f}}=15J\]


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