From: myers@hpfcso.FC.HP.COM (Bob Myers) Date: Sat, 24 Apr 1993 05:24:20 GMT Subject: Re: WD-40 as moisture repellant (was Lead Acid batteries & Concrete?) Message-ID: <7480241@hpfcso.FC.HP.COM> Organization: Hewlett-Packard, Fort Collins, CO, USA Path: cantaloupe.srv.cs.cmu.edu!magnesium.club.cc.cmu.edu!news.sei.cmu.edu!cis.ohio-state.edu!zaphod.mps.ohio-state.edu!howland.reston.ans.net!usc!cs.utexas.edu!sdd.hp.com!hpscit.sc.hp.com!hplextra!hpfcso!myers Newsgroups: sci.electronics References: Lines: 17 > >Please explain how cement is able to maintain a lower average temperature > >than dirt. Sheesh....... > I hope David isn't going to be too upset with me for sticking my nose in here again, but here goes......:-) It isn't the average temperature that is the key factor here, but rather which is better at transferring the heat out of the (presumably warmer than ground temperature) battery. Call it a question of thermal conductivity, or of insulating ability, or "thermal mass" - whatever you like. Question - why does a concrete floor feel cooler than the surrounding dirt when you place your hand on it? Bob Myers KC0EW Hewlett-Packard Co. |Opinions expressed here are not Systems Technology Div. |those of my employer or any other myers@fc.hp.com Fort Collins, Colorado |sentient life-form on this planet.