A block of wood of mass 400 g and density 0.8 g/cm³ is floating on the surface of a liquid of density 1.3 g/cm³.What is the difference in mass of stone (density = 1.9 g/cm³)that must be added to the block in order for the combination (wood and stone)to be just submerged rather than only the wood to be submerged? A)250 g B)540 g C)170 g D)790 g E)none of the above

Question

Quizplus · Accepted Answer

To submerge the wood, the weight of the displaced liquid must equal the weight of the wood plus the stone. The volume of the wood is 500 cm³ (400 g / 0.8 g/cm³). The weight of the displaced liquid when the wood is submerged is 650 g (500 cm³ * 1.3 g/cm³). Therefore, the stone must weigh 250 g (650 g - 400 g) to submerge the wood. The mass of the stone is 540 g (250 g / (1.9 g/cm³ / 1.3 g/cm³)).

A Block of Wood of Mass 400 G and Density