Mu slinging

[John Walker <acad!throop!kelvin>]

>> I meant, what is the variable (Mu) normally associated with in physics (if
>> anything)?

1.  As the SI standard abbreviation for "micro".
2.  A lepton with 207 times the mass of the electron (formerly called
    "mu meson", now usually "muon").  Nonetheless, the greek letter
    "mu" is still used.
3.  In electromagnetism, for magnetic permeability.  Hence "mu metal"
    for magnetic shielding material.
4.  In mechanics, the coefficient of friction.