To the OP (and anyone else confused by g and gc
, where the factors of 32 go) in fluid mechanics, read the above sentence over & over again until it sinks in.
As far as changing from inch to metric/SI goes, I think it would have happened a long time ago if the Earth's circumference had worked out to 2.56 cm per inch rather than the 2.54 factor we have. At 2.56, you could cut "metric" threads on an inch screw lathe using the normal set of change gears; with the 2.54 factor you need a 127 tooth gear - harder to make and if you do make one, it is too big in diameter to fit in the lathe gearbox. Thousands of factories and shops with probably millions of expensive lathes and mills = lots of resistance to changing standards. With modern CNC stuff it doesn't matter anymore, but for essentially all of the 20th century it did.