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Systems of Particles and Rotational Motion — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysicsSystems of Particles and Rotational Motion1 Mark
MCQ
Let $\overrightarrow{\text{A}}$ be a unit vector along the axis of rotation of a purely rotating body and $\overrightarrow{\text{B}}$ be a unit vector along the velocity of a particle $P$ of the body away from the axis. The value of $\overrightarrow{\text{A}}.\overrightarrow{\text{B}}$ is:
  • A
    $1$
  • B
    $-1$
  • ✓
    $0$
  • D
    None of these.
✓

Answer

Correct option: C.
$0$
For a purely rotating body, the axis of rotation is always perpendicular to the velocity of the particle. Therefore, we have:
$\overrightarrow{\text{A}}.\overrightarrow{\text{B}}=0$

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