Question

the figure below to the left shows a beaker completely filled with water. then a block of wood is gently lowered into the beaker until it floats on its own. explain what happens to the reading on the scale after the block floats in the water, compared to the original reading. assume any water that is displaced from the beaker drains to the floor. hint: think along the lines of archimede's principle

Answer 1

As the wood is lowered into the beaker, the wood displaces some of the water in the beaker. The volume of water displaced is equal to the volume of the block which is submerged in the water. According to archimede's principle, the buoyancy force on a submerged object is equal to the displaced weight of the liquid. Since the block is floating freely, this means that the buoyancy force acting on the block is equal to the weight of the block. So the water that is displaced from the beaker also has the same mass as the block. Hence the final mass of the system will remain the same.