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NEET Sample Paper NEET Sample Test Paper-42

  • question_answer
    A uniform force of \[\left( 3\hat{i}+\hat{j} \right)N\]acts on a particle of mass 2kg. Hence, the particle is displaced from position \[\left( 2\hat{i}+\hat{k} \right)m\]to position\[\left( 4\hat{i}+3\hat{j}-\hat{k} \right) m\]. The work done by the force on the particle is:

    A) 9J          

    B)                           6J

    C) 13J                              

    D) l5J

    Correct Answer: A

    Solution :

    \[\operatorname{F}=\left( 3\hat{i}+\hat{j} \right)\operatorname{N}\] \[{{\vec{r}}_{l}}=2\hat{i}+\hat{k}{{\vec{r}}_{2}}=4\hat{i}+3\hat{j}-\hat{k}\] \[\Delta \vec{r}={{\vec{r}}_{2}}-{{\vec{r}}_{1}}\] \[=4\hat{i}+3-\hat{k}-2\hat{i}-\hat{k}\] \[\Delta \vec{r}=2\hat{i}+3j-2\vec{k}\] \[\operatorname{W}=\vec{F}.\vec{r}\] \[\operatorname{W}=\left( 3\hat{i}+\hat{j} \right)\left( 2\hat{i}+3\hat{j}-2\hat{k} \right)\] \[\operatorname{W}=6+3=9J\]


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