Final answer:
The question seems to pertain to a marine engineering exercise involving an LRU-16P buoyancy tube twist check,
Step-by-step explanation:
The question appears to be about a practical exercise in a marine engineering or naval subjects which involves understanding the principles of buoyancy by conducting an LRU-16P buoyancy tube twist check. However, the details provided are insufficient to deliver a precise answer about the size and positioning of the blocks used in this particular check.
Performing an LRU-16P buoyancy tube twist check would typically refer to a maintenance or inspection process for a type of flotation device used in marine applications, often in military or rescue operations.
If this is an experimental procedure, comparing the mass of a foam block to the mass of displaced water is fundamentally an exercise in understanding Archimedes' principle, which is key to buoyancy.
In a typical buoyancy experiment, a foam block's mass can be compared with the mass of the water it displaces to demonstrate that a floating object displaces an amount of fluid that is equal to its own mass.
Without specific information on the LRU-16P buoyancy tube twist check, this explanation is based on general engineering principles involving flotation and buoyancy.