Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site mit-eddie.UUCP Path: utzoo!linus!philabs!cmcl2!harvard!think!mit-eddie!jbs From: jbs@mit-eddie.UUCP (Jeff Siegal) Newsgroups: net.puzzle,net.math Subject: Re: Re: Polar Bear Problem Sequel Message-ID: <294@mit-eddie.UUCP> Date: Sat, 2-Nov-85 16:10:43 EST Article-I.D.: mit-eddi.294 Posted: Sat Nov 2 16:10:43 1985 Date-Received: Tue, 5-Nov-85 05:28:11 EST References: <361@proper.UUCP> <367@faron.UUCP> <10755@ucbvax.ARPA> <42@nbs-amrf.UUCP> <541@ttrdc.UUCP> Reply-To: jbs@mit-eddie.UUCP (Jeff Siegal) Distribution: net Organization: MIT, Cambridge, MA Lines: 19 Xref: linus net.puzzle:1054 net.math:2105 In article <541@ttrdc.UUCP> levy@ttrdc.UUCP (Daniel R. Levy) writes: >...with ordinary glass when it is heated, often resulting in >shattering [BTW, can anyone tell why it is that ordinary glass will >break when heated, but the same glass was successfully cooled into that >shape from a molten blob or sheet?].) Anyhow, some glasses, like Pyrex, >are much less subject to this since they expand much less when heated than >ordinary glass. The internal forces would constrain the "filler" piece >of material to be a slightly different shape when an integral part of the >whole than if heated by itself. Just ramblin' on... The glass doesn't shatter becuase from expansion, but rather, from _uneven_ expansion. If the glass is heated sufficiently evenly or sufficiently slowly (so the heat is conducted throughout the glass), it will not shatter. Thermal expansion really is like a photo-reducing and photo-increasing copy machine, only one that works in three dimensions. Jeff Siegal - MIT EECS