Find the minimum force required to drag a hard polythene plate of area 2 ${\mathrm{m}}^2$ on a thin film of oil of thickness 0.25 cm and $\mathrm{\eta }$ = 15 poise. Assume the speed of the plate is 10 cm/s.

• A

  $2.4\times {10}^7 \mathrm{dyne}$

• B

  $1.8\times {10}^7 \mathrm{dyne}$

• C

  $1.2\times {10}^7 \mathrm{dyne}$

• D

  $6.0\times {10}^6 \mathrm{dyne}$