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JEE Main & Advanced JEE Main Paper (Held On 10-Jan-2019 Evening)

  • 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 Online Paper (Held On 10-Jan-2019 Evening]

    A) 9 J                               

    B) 10 J  

    C) 12 J     

    D)                  15 J

    Correct Answer: D

    Solution :

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


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