The terminal velocity of a 2 cm radius ball in a viscous liquid is 20 $\mathrm{cm} {\mathrm{s}}^{-1}$. What would be the terminal velocity if the radius of the ball were halved?

• A

  80 $\mathrm{cm} {\mathrm{s}}^{-1}$

• B

  40 $\mathrm{cm} {\mathrm{s}}^{-1}$

• C

  20 $\mathrm{cm} {\mathrm{s}}^{-1}$

• D

  5 $\mathrm{cm} {\mathrm{s}}^{-1}$