Subclass relation between Pressure and Force appears to be mistaken

[gregfowlerphd]

I began to worry about the subclass relation because of the definition for pressure, according to which a pressure is a ‘Force that is applied perpendicular to the surface of an Object per unit area over which that Force is distributed’. The italicized phrase indicates that measurement units of pressure will not be the same as measurement units of force, in which case pressure would seem not to be a subclass of force. Having looked into it further has confirmed my suspicion that it isn’t.

Hence, I recommend removing the subclass assertion and modifying the Pressure definition, perhaps as follows:

A Process Profile that is characterized by the Force applied perpendicular to the surface of an Object per unit area over which that Force is distributed.

[alanruttenberg]

I'm not sure why these are process profiles at all. Seems to me they are closer to dispositions.

[gregfowlerphd]

@alanruttenberg: I suspect the reason is that they are measured in units that are per second squared, suggesting that they involve the temporal dimension and hence are occurrents.

[alanruttenberg]

pressure changes. processes don't. the barometric pressure maintains identity while changing moment to moment, the hallmark of a continuant.

[alanruttenberg]

as another example weight is a continuant and is mass times g. g is an acceleration.

[alanruttenberg]

look up the SI unit for Ohm - unit of electrical resistance, clearly a continuant. summary: presence of time in units does not a process make

[gregfowlerphd]

@alanruttenberg: Those are all fair points.