RAJASTHAN ­ PET Rajasthan PET Solved Paper-2006

  • question_answer
    The position vector of the particle is\[r=(a\cos \,\,\omega t\,)\,\overset{\hat{\ }}{\mathop{i}}\,\,(a\,\sin \,\omega t)\,\overset{\hat{\ }}{\mathop{j}}\,.\] The velocity of particle is

    A)  parallel to position vector

    B)  perpendicular to position vector

    C)  along the origin

    D)  along to opposite of origin

    Correct Answer: B

    Solution :

     \[\overrightarrow{r}=(a\cos \omega t)\hat{i}+(a\sin \omega t)\hat{j}\] \[\overrightarrow{v}=\frac{d\overrightarrow{r}}{dt}=-(a\omega \sin \omega t)\hat{i}+(a\omega \cos \omega t)\hat{j}\] \[{{m}_{1}}=\frac{a\sin \omega t}{a\cos \omega t}=\tan \omega t\] \[{{m}_{2}}=\frac{a\omega \cos \omega t}{-a\omega \sin \omega t}=-\cot \omega t\] \[\therefore \] \[{{m}_{1}}{{m}_{2}}=-1\] Therefore, velocity of particle will be perpendicular to position vector.


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