Definition:FPS/Base Units
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Definition
The base FPS units are as follows:
Name | Unit symbol | Dimension | Symbol |
---|---|---|---|
foot | $\mathrm {ft}$ | Length | $l$ |
pound | $\mathrm {lb}$ | Mass | $m$ |
second | $\mathrm s$ | Time | $t$ |
Foot
The foot is the FPS base unit and an imperial unit of length.
\(\ds \) | \(\) | \(\ds 1\) | foot | |||||||||||
\(\ds \) | \(=\) | \(\ds 12\) | inches | |||||||||||
\(\ds \) | \(=\) | \(\ds \dfrac 1 3\) | yard | |||||||||||
\(\ds \) | \(=\) | \(\ds 30 \cdotp 48\) | centimetres | \(\quad\) (exact) | ||||||||||
\(\ds \) | \(=\) | \(\ds 0 \cdotp 3048\) | metres | \(\quad\) (exact) |
Pound
The pound is the FPS unit of measurement of mass, which has a number of different standards.
The most common standard is for it to be defined in kilograms to be exactly $0.453 \, 592 \, 37 \ \mathrm{kg}$.
Second
The second is the SI base unit of time, and also therefore of the MKS system.
It is also the base unit of time for the FPS and CGS systems.
The second is defined as:
- the duration of $9 \ 192 \ 631 \ 770$ periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium $133$ atom at rest at $0 \ \mathrm K$.