A wheel of radius r rolls without slipping on the ground with speed v. When it is at point p, a piece of mud flies off tangentially from its highest point, and lands on the ground at a point Q. The distance PQ is

• A

  $2\mathrm{v}\sqrt{\frac{\mathrm{r}}{\mathrm{g}}}$

• B

  $2\sqrt{2}\mathrm{v}\sqrt{\frac{\mathrm{r}}{\mathrm{g}}}$

• C

  $4\mathrm{v}\sqrt{\frac{\mathrm{r}}{\mathrm{g}}}$

• D

  $\mathrm{v}\sqrt{\frac{\mathrm{r}}{\mathrm{g}}}$