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Howto calculate density in the IPS system by kellnerp
Posted: 23 Jan 12

(1)    P = ρgh

so for water in the IPS system:
       ρ = 62.4 lbm/ft3 / (1,728 in3/ft3) / 386.16 lbm/slinch = 0.000094 slinch/in3
(2)    F=ma    so    F/m=32.18 ft/s2*12 in/ft = 386.16 lb/slinch

which gives, for a one inch water column in an inertial frame on the earth's surface:

       0.001122 slinch/in3 * 386.16 in/s2 = 0.0361 lb/in2

which is about what you would expect.

†    "slinch" is a slang word for the mass unit in the IPS system since there is no formal word for mass in this system.

Note:    People brought up in the English system confuse force with mass, while many people brought up in the metric system confuse mass with force, eg, torque wrenches calibrated in kg-m.
Nobody said the Imperial (IPS) units were easy.


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