The utility illustrates Archimedes' principle as discussed in Section 10.3.
The floating block has a density less than or equal to that of water.
When placed in water, the amount of liquid displaced (and collected in the
overflow container to the left of the bucket of water) is equal in volume
to the volume of the submerged portion of the block. The pressure in the
liquid as a function of depth is shown on the graph to the right of the
bucket. Note that it follows the linear behavior discussed in Section
10.1, Equation 10.3.
The oscillatory behavior obtained by pushing the block below its equilibrium
position is discussed in chapter 14 and problem 14.36.