A cubical block of wood 10 cm on a side floats at the interface between oil and water with its lower surface horizontal and 4 cm below the interface. The density of oil is0.6 g cm−3. The mass of block is
760 g
Weight of block = Weight of displaced oil + Weight of displaced water
⇒ mgV1p0g+V2pwg
⇒ m=(10×10×6)×0.6+(10×10×4)×1=760g.