# Talk:Tension (physics)

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## Relationship to Other Articles

This article has overlapping content with other pages and work is needed to identify where and how overlapping topics are addressed differently on these pages and how/where/whether they reference each other.

Sustain4people (talk) 14:15, 27 April 2014 (UTC)

## Tension - units of measurement

The page on tension requires units of measurement N/m It would also be useful to indicate that in some circumstances - such as in the determination of plate vibration characteristics (for example, analysis by Timoshenko) it is more appropriate to use tensile stress with units of N/m^2

In a microphone diaphragm - the "tension" or stress in the diaphragm can be characterised by both tension N/m or tensile stress N/m^2

From a measurement point of view it is practical to measure the diaphragm tension N/m

From an analysis point of view it is useful to use the units N/m^2

It is also worth pointing out that tensile stress and Pressure (distributed over a diaphragm surface) both use the units N/m^2

georgerai at hotmail dot com

The magnitude of the force of tension typically increases with the amount of stretching. For small stretching, the force is often described by Hooke's law. If this means that the amount of stretch usually increases with tension, than we should change it to say that. I think this is confusing.69.122.62.231 (talk) 21:52, 8 July 2008 (UTC)

I agree with above. Tension really relates to force per unit length (eg surface tension). The main article on tension claims that it is the same as force, eg reactive force in a string holding a weight. Tension should be differentiated from Stress also. 203.206.65.62 (talk) 13:37, 31 July 2008 (UTC)

This is a high-school Physics definition of tension -- a force applied by a string/cable to some object. The article neither defines tension clearly (so as to preclude other definitions) nor does it elucidate clearly exactly what it is. The definition itself needs work. —Preceding unsigned comment added by Munshisan (talkcontribs) 17:36, 13 October 2010 (UTC)

I do not think tension is force, because it is a not a vector. It is a scalar function of position along a string or other one dimensional continuous material. Tension has units of force, e.g. Newtons. The talk page seems to have general agreement that the existing page is wrong and wishing for someone to take a brushstroke at it. I'm willing! MIT '91 Course VIII! --Sustain4people (talk) 03:34, 27 April 2014 (UTC)Sustain4people

## Conservative or non conservative?

Please specify whether the tension force is conservative or non conservative. 07:52, 13 February 2010 117.96.214.194 (talk) [added]

It is not conservative. Energy, momentum, and angular momentum are conserved, and tension is none of these. Strictly thinking I believe it should probably be defined in terms of the stress tensor in continuum mechanics, which is itself distantly related to the stress-energy tensor of general relativity. Wwheaton (talk) 09:47, 26 February 2011 (UTC)

this article is very usefull Tension isn't a force, that much should be readily apparent, since it doesn't have a direction, but only an axis. The first two paragraphs don't say anything about tension, merely talking clumsily about free-body diagrams, and the last paragraph about string theory is totally wtf. Unfortunately, I'm not smart enough to fix it; if I understood continuum mechanics, I wouldn't be whining on the talk page. But someone who knows better shouldn't hesitate to come along and replace the whole thing with something that makes sense. 24.91.116.134 (talk) 21:47, 20 February 2011 (UTC)

Quite. I guess I think it should follow the K.I.S.S. (Keep It Simple, Stupid) principle, and simply give the obvious distinction between tension and compression (and maybe mention shear). It might be worthwhile to outline the important distinction between structures in compression and in tension ("strength of materials"). Then wikilink to the stress tensor, which is really the key step beyond, but mathematically much more complex. I would suppress the string theory material altogether, as uselessly specialized and confusing to the vast majority of readers, and reachable through the stress tensor link for others. Wwheaton (talk) 22:08, 25 February 2011 (UTC)
Tension absolutely is a force (or set of forces). Consider a string from A to B to C. If you pull A to the left and C to the right, this creates a tension in the string. The part AB exerts an attractive force on the part BC (pulling BC to the left). And the part BC exerts an attractive force on the part AB (pulling AB to the right). Remember for every action (force) there is an equal and opposite reaction. The mere fact that these are opposite to each other does not mean that they "cancel out" to nothing (or no direction). Just consider what would happen if you suddenly cut the string at BAB and BC would separate which shows that they were being held together by force before the cutting.
At the molecular level, the tension is composed of electrostatic attraction and electron exchange forces. JRSpriggs (talk) 11:37, 26 February 2011 (UTC)
Hmmm. But a set of 3-vectors is not a 3-vector, and a set of forces is not properly "a force", no? And even in the simplest one-dimensional case of a fiber or string, you have to have at least two opposing forces (two vectors, adding to sum to the zero vector) to have a non-zero tension. For a single unbalanced force (as, if you cut the string), the tension becomes zero. The stress tensor can certainly be described in terms of a set of force vectors, but is not a 3-space vector itself. I think that is probably what 24.91.116.134 (talk) had in mind, and why I agreed with him. (Of course a set of vectors can be regarded as a higher dimensional vector in a different abstract vector space, and a tensor is a vector from that point of view, but I think that is not what we are talking about here, yes? I hope we agree that a set of forces is not "a force"?) So I think calling tension "a force" is an imprecise blurring of terminology, likely to confuse. Wwheaton (talk) 03:22, 28 February 2011 (UTC)
I agree with you Wwheaton, "tension" and "compression" are not forces. I'm an engineer, so I don't understand all of the 3-vector and tensor stuff you are talking about, but from my more practical POV we engineers discuss items being under compression or tension, without regard to the forces. However, the term can be used to describe a force, e.g. "a tensile force", but I still wouldn't call "tension" or "compression" a force. Wizard191 (talk) 19:24, 4 March 2011 (UTC)
I think 90% of readers coming to this topic will be looking for the simplest, engineering level explanation. The next step beyond that is the stress tensor of continuum mechanics. Deeper levels still of physics and mathematics (really beyond my everyday competence), are the Maxwell stress tensor of electromagnetism and the stress–energy tensor of General Relativity, which would finally connect to string theory. In my opinion we ought to give a clear and simple explanation here of that first level (also clearly explaining the distinction between "stress" [ie, force fields in materials] and "strain" [geometric deformation]), plus a few sentences to explain the need for the next level (the stress tensor, which handles shearing and twisting forces in materials), and just link out to our WP articles on the EM & GR concepts, that are related generalizations, but more distant for almost everyone. The lovely thing about hypertext is of course that we do not have to clutter up this article with every detail and lose the central simplicity, but can simply link to the more difficult material, only warning readers that it is there if they need to study it. Those articles already exist, in all their glory.
Before reforming the article, does this outline seem right to other editors? That is:
• Define and explain the core concepts (compression, tension, stress, strain, shear, torsion) at the first-year college physics level,
• briefly describe the stress tensor of continuum mechanics as needed for a more rigorous and complete treatment, and then