What happens to the water level when you place a block of wood in a pail of water? How does the weight of the water that the block of wood displaces compare to the weight of the wood? What would happen to the water level in the pail if more of the floating block was submerged? Consider a block that is no longer floating but is resting on the bottom of the pail. If you kept the volume of the block the same and increased its mass, what would happen to the water level in the pail? Would a block of wood behave the same way in salt water as it does in fresh water?
