Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site ecsvax.UUCP Path: utzoo!watmath!clyde!bonnie!akgua!mcnc!ecsvax!hes From: hes@ecsvax.UUCP (Henry Schaffer) Newsgroups: net.puzzle Subject: Re: Thermometer Puzzle **SPOILER** Message-ID: <633@ecsvax.UUCP> Date: Fri, 25-Oct-85 21:50:52 EDT Article-I.D.: ecsvax.633 Posted: Fri Oct 25 21:50:52 1985 Date-Received: Sat, 26-Oct-85 19:45:21 EDT References: <24@pixel.UUCP> Distribution: net Organization: NC State Univ. Lines: 15 > When an ordinary mercury thermometer at room temperature is inserted > into a beaker of boiling water, the mercury actually descends a > small but noticeable amount before ascending to the 100 C level. > Why? > > Steve Harris Before the mercury can expand because of the heat, the glass surrounding the mercury must get hot to pass on the heat. The glass does expand somewhat *before* the mercury heats up. This expansion increases the volume of the "container" holding the mercury, and so the mercury will descend. For a small (rate of) change in the temperature the effect should be very small, but room temp. to boiling water is not a small change. --henry schaffer