Verskil tussen weergawes van "Wringkrag"

26 grepe bygevoeg ,  3 jaar gelede
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Die gevolg van beide hierdie definisies is dat wringkrag 'n vektor is, wat in die rigting van die as van die draaibeweging wat dit sal veroorsaak.
 
== Eenhede ==
Wringkrag het dimensies van krag vermenigvuldig met [[afstand]] en die [[SI|SI-eenhede]] van wringkrag word geskryf as "[[newton meter]]" (N&nbsp;m of N·m).<ref name="BIPM 5.1">SI Brosjure Weergawe 8, Afdeling 5.1, Bureau International des Poids et Mesures, 2006, [http://www1.bipm.org/en/si/si_brochure/chapter5/5-1.html], afgelaai 2007-04-01</ref>
 
Ander nie SI-eenhede van wringkrag sluit in "[[pondkrag]]-[[voet]]" of "voet-pondkrag" of "onskrag-duime" of "meter-kilogramkrag".
 
== Spesiale gevalle en ander feite ==
===Moment-arm formule===
[[Beeld:Moment arm af.png|thumb|right|250px|Moment-arm diagram]]
As iemand byvoorbeeld 'n krag van 10 N op 'n moersleutel wat 0.5 meter lank is, uitoefen, sal die wringkrag 5 N·m wees, met die aanname dat die persoon wat die moersleutel trek die krag loodreg op die moersleutel uitoefen.
 
=== Krag teen 'n hoek ===
As 'n krag van grootte ''F'' teen 'n hoek θ vanaf die verplasingsarm met 'n lengte ''r'' uitgeoefen word (en op 'n vlak loodreg tot die draai-as), volg uit die definisie van kruisproduk dat die grootte van die wringkrag wat ontstaan as volg is:
 
:<math>\boldsymbol \tau=rF \sin \theta</math>
 
=== Statiese ewewig ===
Vir 'n voorwerp om in [[statiese ewewig]] te verkeer, moet nie net die som van alle kragte nul wees nie, maar ook die som van al die wringkragte (momente) rondom enige punt. Vir 'n twee dimensionele situasie met horisontale en vertikale kragte, lewer die som van kragte vereiste twee vergelykings:Σ''H'' = 0 and Σ''V'' = 0 en die wringkrag 'n derde vergelyking:Σ''τ'' = 0. Drie vergelykings word dus benodig om 'n statiese bepaalde ewewigsprobleem op te los.
 
=== Wringkrag as 'n funksie van tyd ===
[[Beeld:PrecessionOfATop.svg|thumb|right|300px|Die wringkrag wat veroorsaak word deur twee teenoorgestelde kragte '''F'''<sub>g</sub> en -'''F'''<sub>g</sub> veroorsaak 'n verandering in hoekmomentum '''L''' in die rigting van daardie wringkarg.]]
Wringkrag is 'n tyd-[[afgeleide]] van [[hoekmomentum]], net soos krag 'n tyd-afgeleide is van [[momentum|linêere momentum]] is:
where '''α''' is [[angular acceleration]], a quantity usually measured in [[radian]]s per [[second]] squared.
 
== Machine torque ==
Torque is part of the basic specification of an [[engine]]: the [[power (physics)|power]] output of an engine is expressed as its torque multiplied by its rotational speed. [[internal combustion|Internal-combustion]] engines produce useful torque only over a limited range of rotational speeds (typically from around 1,000–6,000 rpm for a small car). The varying torque output over that range can be measured with a [[dynamometer]], and shown as a torque curve. The peak of that torque curve usually occurs somewhat below the overall power peak. The torque peak cannot, by definition, appear at higher rpm than the power peak.
 
Torque is also the easiest way to explain [[mechanical advantage]] in just about every [[simple machine]].
 
== Relationship between torque, power and energy ==
 
If a [[force]] is allowed to act through a distance, it is doing [[mechanical work]]. Similarly, if torque is allowed to act through a rotational distance, it is doing work. [[Power (physics)|Power]] is the work per unit [[time]]. However, time and rotational distance are related by the [[angular speed]] where each revolution results in the [[circumference]] of the circle being travelled by the force that is generating the torque. This means that torque that is causing the angular speed to increase is doing work and the generated power may be calculated as:
Also, the unit newton-metre is [[dimensional analysis|dimensionally equivalent]] to the [[joule]], which is the unit of energy. However, in the case of torque, the unit is assigned to a [[vector (spatial)|vector]], whereas for [[energy]], it is assigned to a [[scalar]].
 
=== Conversion to other units ===
For different units of power, torque, or [[angular speed]], a conversion factor must be inserted into the equation. Also, if [[rotational speed]] (revolutions per time) is used in place of angular speed (radians per time), a conversion factor of <math>2 \pi</math> must be added because there are <math>2 \pi</math> radians in a revolution:
 
Use of other units (e.g. [[BTU]]/h for power) would require a different custom conversion factor.
 
=== Derivation ===
For a rotating object, the ''linear distance'' covered at the [[circumference]] in a [[radian]] of rotation is the product of the radius with the angular speed. That is: linear speed = radius x angular speed. By definition, linear distance=linear speed x time=radius x angular speed x time.
 
because <math>5252.113... = \frac {33,000} {2 \pi} \,</math>.
 
== See also ==
*[[Angular momentum]]
*[[Mechanical equilibrium]]
*[[Torsion]]
 
== Notes ==
<references/>
 
== References ==
*{{cite book | author=Serway, Raymond A.; Jewett, John W. | title=Physics for Scientists and Engineers (6th ed.) | publisher=Brooks/Cole | year=2004 | id=ISBN 0-534-40842-7}}
*{{cite book | author=Tipler, Paul | title=Physics for Scientists and Engineers: Mechanics, Oscillations and Waves, Thermodynamics (5th ed.) | publisher=W. H. Freeman | year=2004 | id=ISBN 0-7167-0809-4}}
 
== External links ==
*[http://craig.backfire.ca/pages/autos/horsepower "Horsepower and Torque"] An article showing how power, torque, and gearing affect a vehicle's performance.
*[http://www.lightandmatter.com/html_books/2cl/ch05/ch05.html a discussion of torque and angular momentum in an online textbook]
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== Verwysings ==
{{verwysingsVerwysings}}
 
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