A plank is resting on a horizontal ground in the northern hemisphere of the earth at a $45^{\circ}$ latitude. Let the angular speed of the earth be $\omega$ and its radius $r_e$. The magnitude of the frictional force on the plank will be
  • A$m r_e \omega^2$
  • B$\frac{m r_e \omega^2}{\sqrt{2}}$
  • C$\frac{m r_e \omega^2}{2}$
  • D
    zero
KVPY 2013, Advanced
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