Editing Q factor (section)

== Mechanical systems ==
For a single damped mass-spring system, the {{mvar|Q}} factor represents the effect of simplified [[viscosity|viscous]] damping or [[Drag (physics)|drag]], where the damping force or drag force is proportional to velocity. The formula for the {{mvar|Q}} factor is:
<math display="block">Q = \frac{\sqrt{M k}}{D}, \,</math><!-- To derive this equation, go to the reference link and substitute eqn (2) into eqn (3), then simplify -->
where {{mvar|M}} is the mass, {{mvar|k}} is the spring constant, and {{mvar|D}} is the damping coefficient, defined by the equation {{math|1= ''F''<sub>damping</sub> = −''Dv''}}, where {{mvar|v}} is the velocity.<ref>[http://units.physics.uwa.edu.au/__data/page/115450/lecture5_(amplifier_noise_etc).pdf Methods of Experimental Physics – Lecture 5: Fourier Transforms and Differential Equations] {{webarchive|url=https://web.archive.org/web/20120319163127/http://units.physics.uwa.edu.au/__data/page/115450/lecture5_(amplifier_noise_etc).pdf|date=2012-03-19|title=}} ([[PDF]])</ref>