Editing Pendulum (section)

=== Simple gravity pendulum {{anchor|Simple}} ===

The ''simple gravity pendulum''<ref>defined by Christiaan Huygens: {{cite web
 | last = Huygens | first = Christian
 | title = Horologium Oscillatorium
 | website = 17centurymaths
 | publisher = 17thcenturymaths.com
 | year = 1673
 | url = http://www.17centurymaths.com/contents/huygens/horologiumpart4a.pdf
 | access-date = 2009-03-01
}}, Part 4, Definition 3, translated July 2007 by Ian Bruce
</ref> is an idealized mathematical model of a pendulum.<ref name="Hyperphysics">{{cite web
 | last = Nave | first = Carl R.
 | title = Simple pendulum
 | website = Hyperphysics
 | publisher = Georgia State Univ.
 | year = 2006
 | url = http://hyperphysics.phy-astr.gsu.edu/hbase/pend.html
 | access-date = 2008-12-10
}}</ref><ref>{{cite web
 | last = Xue | first = Linwei
 | title = Pendulum Systems
 | website = Seeing and Touching Structural Concepts
 | publisher = Civil Engineering Dept., Univ. of Manchester, UK
 | year = 2007
 | url = http://www.mace.manchester.ac.uk/project/teaching/civil/structuralconcepts/Dynamics/pendulum/pendulum_con.php
 | access-date = 2008-12-10
}}</ref><ref>{{cite web
 | last = Weisstein | first = Eric W.
 | title = Simple Pendulum
 | website = Eric Weisstein's world of science
 | publisher = Wolfram Research
 | year = 2007
 | url = http://scienceworld.wolfram.com/physics/SimplePendulum.html
 | access-date = 2009-03-09
}}</ref> This is a weight (or [[Bob (physics)|bob]]) on the end of a massless cord suspended from a [[wikt:pivot|pivot]], without [[friction]]. When given an initial push, it will swing back and forth at a constant [[amplitude]]. Real pendulums are subject to friction and [[air drag]], so the amplitude of their swings declines.

{{multiple image
<!-- Essential parameters -->| align             = right
| direction         = vertical
<!-- Header -->| header            = Pendulum
<!-- Images -->| width             = 200
| image1            = PenduloTmg.gif
| caption1          = Animation of a pendulum showing forces acting on the bob: the tension ''T'' in the rod and the gravitational force ''mg''.
| image2            = Oscillating pendulum.gif
| caption2          = Animation of a pendulum showing the [[Equations of motion|velocity]] and acceleration vectors
}}