Which principle is used to separate kerosene/oil and water?

kerosene/oil and water differ in their densities, therefore they can be separated by a separating funnel. A separating funnel, also called separating funnel, separating funnel or generally called sep-funnel, is a piece of laboratory glassware used in liquid-liquid extractions to separate (divide) the components of a mixture into two immiscible solvent phases with different densities.