https://wiki.sarg.dev/api.php?action=feedcontributions&feedformat=atom&user=73.38.222.15 2026-08-04T13:26:50Z User contributions MediaWiki 1.44.2 https://wiki.sarg.dev/index.php?title=Craig_Spence&diff=597556 2023-05-02T20:31:58Z

<p>73.38.222.15: formatting</p> <hr /> <div>'''Craig Spence''' may refer to:<br /> *[[Craig Spence (golfer)]] (born 1974)<br /> *[[Craig Spence (archaeology)]] (fl. 1990–present), historian and archaeologist<br /> *[[Craig J. Spence]] (1940–1989), lobbyist who committed suicide after being named a client of a prostitution ring<br /> <br /> {{hndis|Spence, Craig}}</div>

73.38.222.15 https://wiki.sarg.dev/index.php?title=Fragile_matter&diff=481982 2021-10-12T00:46:43Z

<p>73.38.222.15: bullet</p> <hr /> <div>In [[materials science]], '''fragile matter''' is a [[granular material]] that is jammed solid. Everyday examples include [[bean]]s getting stuck in a hopper in a whole food shop, or milk powder getting jammed in an upside-down bottle. The term was coined by physicist [[Michael Cates]], who asserts that such circumstances warrant a new class of materials. The jamming thus described can be unjammed by mechanical means, such as tapping or shaking the container, or poking it with a stick.<br /> <br /> Cates proposed that such jammed systems differ from ordinary solids in that if the direction of the applied [[stress (physics)|stress]] changes, the jam will break up. Sometimes the change of direction required is very small.<br /> <br /> Perhaps the simplest example is a pile of [[sand]], which is solid in the sense that the pile sustains its shape despite the force of gravity. Slight tilting or vibration is enough to enable the grains to shift, collapsing the pile.<br /> <br /> Not all jammed systems are fragile, i.e. [[foam]]. [[Shaving]] foam is jammed because the bubbles are tightly packed together under the [[isotropic]] stress imposed by [[atmospheric pressure]]. If it were a fragile solid, it would respond [[plastic]]ally to [[shear stress]], however small. But because bubbles deform, foam actually responds [[Elasticity (physics)|elastically]] provided that the stress is below a threshold value. Fragile matter is also not to be confused with cases in which the particles have adhered to one another (&quot;caking&quot;). <br /> <br /> ==References==<br /> * {{cite book<br /> |last = Cates<br /> |first = Michael<br /> |authorlink = Michael Cates<br /> |title = Soft and Fragile Matter<br /> |publisher = [[CRC Press]]<br /> |year = 2000<br /> |isbn = 0-7503-0724-2}}<br /> [[Category:Granularity of materials]]</div>

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