Pressure = (force) divided by (area)
But force and area are both derived units themselves.
-- Force = (mass) times (acceleration)
But acceleration is a derived unit itself.
Acceleration = (length) divided by (time squared)
So force = (mass) · (length / time squared)
-- Area = (length squared)
So pressure = (mass · length / time-squared) / (length-squared)
Pressure = (mass) / (length · time-squared)
That sure looks to me like it's derived from a bunch of other stuff.
