From owner-freebsd-hardware@FreeBSD.ORG Fri Aug 18 17:39:51 2006 Return-Path: X-Original-To: freebsd-hardware@freebsd.org Delivered-To: freebsd-hardware@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id DB3CB16A4DF for ; Fri, 18 Aug 2006 17:39:51 +0000 (UTC) (envelope-from mitchell@cloudynwuk.force9.co.uk) Received: from pih-relay05.plus.net (pih-relay05.plus.net [212.159.14.132]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5976043D66 for ; Fri, 18 Aug 2006 17:39:50 +0000 (GMT) (envelope-from mitchell@cloudynwuk.force9.co.uk) Received: from [81.174.214.211] (helo=hal) by pih-relay05.plus.net with esmtp (Exim) id 1GE8Jw-000791-J0; Fri, 18 Aug 2006 18:39:49 +0100 Received: from 127.0.0.1 (AVG SMTP 7.1.405 [268.11.3/423]); Fri, 18 Aug 2006 18:39:46 +0100 Message-ID: <000101c6c2ed$4c2700a0$d3d6ae51@hal> From: "Frank Mitchell" To: Date: Fri, 18 Aug 2006 17:56:49 +0100 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4133.2400 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4133.2400 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=iso-8859-1 Cc: man-lug@lists.man.ac.uk, sc@mailman.lug.org.uk, freebsd-hardware@freebsd.org Subject: Exploding CDs X-BeenThere: freebsd-hardware@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: General discussion of FreeBSD hardware List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 18 Aug 2006 17:39:51 -0000 A recent BBC2 programme: "Mythbusters" explored the rumour that some CD-ROM Drives go so fast they make CDs fly apart. Two Stunt Engineers organised an experiment and showed this actually happens with some brands of CD. Just before disintegrating, these disks assumed a sort of corrugated appearance, which suggests the problem is caused by Resonant Frequency (as with the Tacoma Narrows bridge) rather than "Centrifugal Force". The CD vibrates with alternate sectors oscillating in opposite directions. When the speed of the drive matches the Natural Frequency of the CD, the amplitude of the vibration gets large enough to crack the disk, which then falls to pieces. Does anybody have more information about this? Faictz Ce Que Vouldras: Frank Mitchell -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.405 / Virus Database: 268.11.3/423 - Release Date: 18/08/2006