Two particles each of mass $m$ and charge $q$ are separated by distance $r_1$ and the system is left free to move at $t = 0$. At time $t$ both the particles are found to be separated by distance $r_2$. The speed of each particle is

  • A

    $\frac{{qm}}{{4\pi {\varepsilon _0}{r_1}{r_2}}}$

  • B

    $\frac{q}{{{r_1}{r_2}\sqrt {(r_2^2 - r_1^2)/4\pi {\varepsilon _0m}} }}$

  • C

    $\frac{\sqrt 2q}{{{r_1}{r_2}\sqrt {(r_2^2 - r_1^2)/4\pi {\varepsilon _0m}} }}$

  • D

    none of these

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