Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!news.albasani.net!.POSTED!not-for-mail From: Frederick Williams Newsgroups: sci.logic,rec.puzzles,sci.math.num-analysis,comp.programming Subject: Re: the hourglass problem Date: Thu, 05 Jan 2012 16:27:46 +0000 Organization: albasani.net Lines: 28 Message-ID: <4F05CF82.CF7560B1@btinternet.com> References: <7f48dfe5-ca54-49ca-8cb9-5ae686e96f92@c42g2000prb.googlegroups.com> <4F05AF0A.6BB2B4C3@btinternet.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Trace: news.albasani.net gbJxdyBtXhyTstKFbg9zlcbs0LOU+Q5PrUpUllZNUfc3ci3+hp0zMpFSrUtGBzmeWzgSHhC1NLxHqvRB59Dc4Q== NNTP-Posting-Date: Thu, 5 Jan 2012 16:27:44 +0000 (UTC) Injection-Info: news.albasani.net; logging-data="PE50o26rgXpkkViwu9WO4LZmJRmEwH9LIaLDJ8r/drrRz87VAfA6FL/dNlngvf7lNy9giNrCaSI2n1WzFPwAfKC9FuDaQ0nyF37XaSc+uUJ7edq/dTJgm/yu0X6xIFlF"; mail-complaints-to="abuse@albasani.net" X-Mailer: Mozilla 4.8 [en] (Windows NT 5.0; U) X-Accept-Language: en Cancel-Lock: sha1:V9Mvy+5c1RgsZvDY6fCj1RHTT50= Xref: x330-a1.tempe.blueboxinc.net comp.programming:1223 Patricia Shanahan wrote: > > Frederick Williams wrote: > > RichD wrote: > >> You're given a 7 minute, and a 4 minute, sand > >> hourglass. > > > > What may one do with these hourglasses? Turn them over, certainly, but > > may one place them on their side so that they stop "ticking"? > > > > Could someone with an actual hourglass check whether that works? I would > have thought that most of the time the level of sand in one side would > still be above the hole. If so, does the sand really stop flowing? I have a three minute egg timer the sand in which stops flowing when it is laid on its side even when most of the sand is in one bulb. And even if it didn't, one can place it a little off the horizontal so that the greater part of the sand falls back from the hole a little, but the rest of the sand (the lesser amount) does not get near the hole. That this works may be because of the shape of the bulbs and YBSMV. I write "sand", but it is some finely divided green stuff. -- When a true genius appears in the world, you may know him by this sign, that the dunces are all in confederacy against him. Jonathan Swift: Thoughts on Various Subjects, Moral and Diverting