JEE Main & Advanced Physics Vectors Question Bank Fundamentals of Vectors

  • question_answer The vector that must be added to the vector \[\hat{i}-3\hat{j}+2\hat{k}\] 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 :

                 Unit vector along y axis \[=\hat{j}\] so the required vector \[=\hat{j}-[(\hat{i}-3\hat{j}+2\hat{k})+(3\hat{i}+6\hat{j}-7\hat{k})]\]\[=-\,4\hat{i}-\,2\hat{j}+5\hat{k}\]

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