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JIPMER Jipmer Medical Solved Paper-2012

  • question_answer
    A certain vector in the xy-plane has an x-component of 4 m and a y-component of 10 m. It is then rotated in the xy-plane so that its x-component is doubled. Then, its new y-component is (approximately)

    A)  20 m      

    B)                         7.2 m

    C)  5.0 m                   

    D)         4.5 m

    Correct Answer: B

    Solution :

    Here, \[A=4\vec{i}+10\vec{j}\] \[\therefore \]  \[|A|=\sqrt{{{(4)}^{2}}+{{(10)}^{2}}}=\sqrt{116}\] Now, according to question, \[A=8\vec{i}+n\,\vec{j}\] \[|A|=\sqrt{{{(8)}^{2}}+{{(n)}^{2}}}\] \[\sqrt{116}=\sqrt{64+{{n}^{2}}}\] \[n=\sqrt{116-64}=7.2\,m.\]


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