Answer
See answer.
Work Step by Step
When the aluminum block is submerged in the water, the water exerts an upward force on the block, equal to the weight of the displaced water.
Using Newton’s third law, we see that the block then exerts an equal downward force down on the water.
The left side has 5.0 kg and the right side starts with 4.5 kg, so the system balances when the block displaces 0.50kg of water on the right hand side.
We know that 0.50 kg of displaced water has a volume of 500 cubic centimeters, which is exactly half the volume of the aluminum cube that is provided.
Using a lead cube of the same size makes no difference – when half of the lead cube is underwater, the system is balanced.
