NEET Sample Paper NEET Sample Test Paper-16

  • question_answer The vector that must be added to the vectors \[\hat{j}-3\hat{j}+2\hat{k}\]and \[3\hat{i}-6\hat{j}-7\hat{k}\]so that, the resultant vector is a unit-vector along the Y-axis is

    A) \[4\hat{i}+2\hat{j}+5\hat{k}\]                    

    B) \[-4\hat{i}-2\hat{j}+5\hat{k}\]                                 

    C) \[3\hat{i}+4\hat{j}+5\hat{k}\]                    

    D) Null vector 

    Correct Answer: B

    Solution :

    Let the desired vector be\[\vec{x}.\] \[\hat{i}-3j+2\hat{k}+3\hat{i}+6\hat{j}-7\hat{k}+\vec{x}=\hat{j}\]or \[4\hat{i}+3\hat{j}-5\hat{k}+\vec{x}=\hat{j}\] or, \[\vec{x}=-4\hat{i}-2\hat{j}+5\hat{k}\] Hence, the correction option is (b).

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