Talk:Compression (physics)

Relationship to other physics articles[edit]

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) 14:10, 27 April 2014 (UTC)[reply]

Compressibility is also not mentioned in this article. Jarble (talk) 19:46, 27 January 2024 (UTC)[reply]

Redirected from compressible surface[edit]

If you type "incompressible surface" into Wikipedia, you get a math-related page. If you type in "compressible surface", it redirects to this (non-math-related) page. I suggest that either Compressible surface become a disambiguation page, or a link to Incompressible surface be given at the top of this page (since "compressible surface" redirects here). Adammanifold (talk) 14:01, 15 May 2009 (UTC)[reply]

Compression and expansion can occur simultaneously..[edit]

"Physical compression is the result of the subjection of a material to compressive stress, resulting in reduction of volume." Adding compression to an expanding material will merely slow the expansion. —Preceding unsigned comment added by NOrbeck (talk • contribs) 23:53, 23 July 2010 (UTC)[reply]

Don't forget items that expand when compressed AManWithNoPlan (talk) 15:28, 23 December 2017 (UTC)[reply]

Rarefaction is not the opposite of compression[edit]

This article is linked to from Rarefaction as its "opposite". This article states the opposite of compression is tension and does not mention rarefaction at all. Continuity? —Preceding unsigned comment added by 144.137.115.195 (talk) 01:54, 28 October 2007 (UTC)[reply]

The head claimed that "rarefaction" is the opposite of compression in fluids. That is not correct: rarefaction is a geometrical concept that does not involve forces explicitly. As such it is the opposite of "condensation", "addensation", or "volume contraction".
In sound waves the medium suffers rarefaction half of the time, but is under compression all the time.
The opposite of compression in fluids is rarely observed since most fluids will boil (cavitate) before the pressure gets reaches zero. Unlike solids, a macroscopic traction stress in a liquid does not get spread out over a gazillion atomic bonds, but becomes concentrated on a few bonds that immediately break (i.e. "boil"). Traction in fluids may be detectable for very short times, exploiting viscosity; I don't know. --Jorge Stolfi (talk) 18:21, 25 February 2013 (UTC)[reply]

Allignment, inward, equal, parallel forces[edit]

If the forces are inward, parallel, and balanced (equal), but not and alligned (on the same line), will there not be either a rotation, a shearing, or a twisting deformation, as opposed to the pinching deformation in compression? Or does "balanced" mean "equal, parallel, and alligned"? In any case, we should define "balanced", since it has many meanings, often in the same field. KatieBoundary (talk) 15:49, 13 March 2013 (UTC)[reply]

Those words describe only the simplest case of uniaxial compression; they do not describe biaxial or general compression. "Balanced" in the case of forces means that their sum is zero, which covers all those cases. Even in the uniaxial case, the external forces are usually distributed over two areas (not just two points) of the body, and not always uniformly; so they need not be exactly opposite or parallel. Consider for example the presses used to make synthetic diamonds, some of them have four anvils arranged as a tetrahedron; they are not in "opposite aligned" pairs, but they are balanced and (very) compressive.
However you are right that one should also say "with no net torque" in order for the situation to be static. Finally, note that the technical definition in the second paragraph (in terms of stress) allows compression and shear at the same time. (BTW my spell-checker says that it is "aligned" not "alligned"; is that British spelling?) --Jorge Stolfi (talk) 18:34, 13 March 2013 (UTC)[reply]