Upthrust or buoyancy is defined by some as the upward force on an
object produced by the surrounding fluid (i.e., a liquid or a gas) in
which it is fully, or partially immersed, due to the pressure
difference of the fluid between the top and bottom of the object.
However, this definition has a problem: If the object is at rest at
the bottom of the ocean floor (assuming tight fit) with no fluid at
the bottom of this object, do you agree that there is no upthrust or
buoyancy for this situation?
Upthrust or buoyancy should be better defined as the magnitude of the
weight of fluid displaced by the body instead?