Page Comparison

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The basic units for all {new-tab-link:http://www.csiberkeley.com/}CSI{new-tab-link} Software include force (lbs, kip, N, kN, etc.), length (ft, in, m, mm, etc.), time (second), and temperature (F, C). [Mass|kb:Mass] is then derived from these values.

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Some notes which concern force and *mass units* are as follows:

* lbs and kips are only used as force units, not mass units

* Consistent mass units are force divided by unit acceleration, given as F/(L/T{^}2^), wherein which L is length and T is time. Weight is a force.
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** Given SI units, in wherewhich force is in Newtons (N), the consistent mass unit is N*sec{^}2^/m = kg.
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** Given US Customary, in wherewhich force is in pounds (lbs), the consistent mass unit is lbs*sec{^}2^/ft = slug. Under a unit acceleration, a mass of one slug generates a one pound force. When accelerated by gravity (g), this same mass generates a force of 32.2 lbs.

* The pound-mass unit is not a consistent unit, where 1 slug = 32.2 pound-mass. Additional information is available in the Wikipedia {new-tab-link:http://en.wikipedia.org/wiki/Pound_(force)}Pound (force){new-tab-link} article.

* Weight density has units of F/L{^}3^

* Consistent mass density has units of (F/(L/T{^}2^))/L{^}3^ = F*T{^}2^/L{^}4^

* The relationship between weight and mass, and weight density and mass density, is W = M * g, all in consistent units.
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** To convert weight density W = 150 lbs/ft{^}3^ into mass density (kip-in), the calculation proceeds as follows:
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M = W / g = 150 lbs/ft{^}3^ / (32.2 ft/sec{^}2^) = 4.658 lbs*sec{^}2^/ft{^}4^ \* (kip / 1000 lbs) * (ft / 12 in)^4^ = 2.246E-7 kip*sec{^}2^/in{^}4^


h1. See Also

* [Units FAQ|kb:Units FAQ]