MCQ
For circular motion, if ${\vec a_t},\,{\vec a_c},\,\vec r$ and $\vec v$ are tangential acceleration, centripetal acceleration, radius vector and velocitym respectively, then find the wrong relation
  • A
    ${\vec a_t}.{\vec a_c} = 0$
  • B
    ${\vec a_t}.\vec v$ may be positive or negative
  • ${\vec a_c}.\vec v$ may be positive or negative
  • D
    ${\vec a_c}.\vec v = 0$

Answer

Correct option: C.
${\vec a_c}.\vec v$ may be positive or negative
c
$\overrightarrow{\mathrm{a}}_{\mathrm{t}} \cdot \overrightarrow{\mathrm{a}}_{\mathrm{c}}=0 \quad$ as $\theta=90^{\circ}$

$\overrightarrow{\mathrm{a}}_{\mathrm{c}} \cdot \overrightarrow{\mathrm{v}}=0 \quad$ as $\theta=90^{\circ}$

$\overrightarrow{\mathrm{a}}_{\mathrm{t}} \cdot \overrightarrow{\mathrm{v}}$ may be $+\mathrm{ve}$ or $-\mathrm{ve}$

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