Verskil tussen weergawes van "Wringkrag"

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Die [[joule]] is die SI-eenheid vir [[energie]] of [[meganiese werk|werk]] en kan ook uitgedruk word as N·m, joule word egter nie gebruik om wringkrag uit te druk nie. Aangesien 'n mens aan energie kan dink as die dotproduk van krag en afstand is energie altyd 'n skalaar terwyl wringkrag die kruisproduk is van krag en afstand en is 'n [[pseudovektor]] grootheid.
 
Die dimensionele gelykheid van hierdie eenhede is natuurlik nie blote toeval nie; 'n wringkrag van 1 N·m wat deur 'n volle omwenteling toegepas word sal presies 2π joule vereis. Wiskundig kan dit uitgedruk word as,
 
waar
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:''E'' die energie is
Of course, the dimensional equivalence of these units is not simply a coincidence; a torque of 1 N·m applied through a full revolution will require an [[energy]] of exactly 2π joules. Mathematically,
:''τ'' die wringkrag is
:''θ'' die hoek waardeur beweeg is, in [[radiaal|radiale]]
 
Ander nie SI-eenhede van wringkrag sluit in "[[pondkrag]]-[[voet]]" of "voet-pondkrag" of "onskrag-duime" of "meter-kilogramkrag".
:<math>E= \tau \theta\ </math>
 
==Spesiale gevalle en ander feite==
where
===Moment -arm formulaformule===
[[ImageBeeld:moment arm.png|thumb|right|250px|Moment -arm diagram]]
 
'n Baie nuttige spesiale geval wat dikwels buite fisika as die definisie van wringkrag gebruik word, is as volg:
:''E'' is the energy
:''τ'' is torque
:''θ'' is the angle moved, in [[radian]]s.
 
Other non-SI units of torque include "[[pound-force]]-[[foot (unit of length)|feet]]" or "foot-pounds-force" or "ounce-force-[[inch]]es" or "meter-[[kilogram-force|kilograms-force]]".
 
==Special cases and other facts==
===Moment arm formula===
[[Image:moment arm.png|thumb|right|250px|Moment arm diagram]]
A very useful special case, often given as the definition of torque in fields other than physics, is as follows:
 
:<math>\boldsymbol{\tau} = (\textrm{moment\ arm}) \times \textrm{force}</math>
 
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The construction of the "moment arm" is shown in the figure below, along with the vectors '''r''' and '''F''' mentioned above. The problem with this definition is that it does not give the direction of the torque but only the magnitude, and hence it is difficult to use in three-dimensional cases. If the force is perpendicular to the displacement vector '''r''', the moment arm will be equal to the distance to the centre, and torque will be a maximum for the given force. The equation for the magnitude of a torque arising from a perpendicular force:
 
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