JEE Main & Advanced Physics Two Dimensional Motion Question Bank Self Evaluation Test - Motion in a Plane

  • question_answer
    The vector having magnitude equal to 3 and perpendicular to the two vectors \[\vec{A}=2\hat{i}+2\hat{j}+\hat{k}\] and \[\vec{B}=2\hat{i}-2\hat{j}+3\hat{k}\] is:

    A) \[\pm \,(2\hat{i}-\hat{j}-2\hat{k})~~~\]

    B)        \[\pm \,(3\hat{i}+\hat{j}-2\hat{k})\]

    C) \[-\,(3\hat{i}+\hat{j}-3\hat{k})~\]

    D)        \[(3\hat{i}-\hat{j}-3\hat{k})\]

    Correct Answer: A

    Solution :

    [a] The required vector is, \[=3\frac{(\text{\vec{A}}\times \text{\vec{B}})}{|\text{\vec{A}}\times \text{\vec{B}}|}=3\frac{[(2\hat{i}+2\hat{j}+\hat{k})\times (2\hat{i}-2\hat{j}+3\hat{k})]}{|\text{\vec{A}}\times \text{\vec{B}}|}\] \[=3\frac{(8\hat{i}-4\hat{j}-8\hat{k})}{\sqrt{{{8}^{2}}+{{4}^{2}}+{{8}^{2}}}}=2\hat{i}-\hat{j}-2\hat{k}.\]


You need to login to perform this action.
You will be redirected in 3 sec spinner