NEET Sample Paper NEET Sample Test Paper-39

  • question_answer If\[\vec{F}\]is the force acting on a particle having position vector \[\vec{r}\]and \[\vec{\tau }\]be the torque of this force about the origin, then

    A) \[\vec{r}.\vec{\tau }\ne 0\]and\[\vec{F}.\vec{\tau }=0\]

    B)  \[\vec{r}.\vec{\tau }>0\]and\[\vec{F}.\vec{\tau }<0\]

    C)  \[\vec{r}.\vec{\tau }=0\]and\[\vec{F}.\vec{\tau }=0\]

    D)  \[\vec{r}.\vec{\tau }=0\]and\[\vec{F}.\vec{\tau }\ne 0\]      

    Correct Answer: C

    Solution :

    Torque is an axial vector, i.e., its direction is always perpendicular to the plane containing vectors \[\vec{r}\]and\[\vec{F}.\] Torque is perpendicular to both \[\vec{r}\]and \[\vec{F}\] \[\therefore \] \[\vec{\tau }.\vec{r}=0\] \[\vec{F}=\vec{\tau }=0\]


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