If `V` is Velocity of oil drop , than according to stok's law, the viscous drag force on an oil drop is proportional to

The viscous drag on a spherical body moving with a speed v is proportional to

An oil drop of mass m fall through a viscous medium. The viscous drag force. F is proportional to the velocity of the drop . At the instant it begins to fall the force that acts on the oil drop is (neglect buoyancy)