On Thu 16 Jan 2014 22:32:49 NZDT +1300, Helmut Walle wrote: > Yes, usually we do not think too much about the amount of kinetic > energy stored in a spinning disc... Years ago, a colleague at work > had the drawer of a CD-RW drive on an HP workstation open and eject > the disc while still spinning at full speed. Once the disc touched > the side of the drawer it got propelled across the room by > tangential friction and hit something so hard that the disc broke up > into a shrapnel of pretty sharp-edged splinters. Quite hazardous > really. If you want to get a feel for how much energy that requires > try breaking a CD by bending it, but if you do PLEASE WEAR ADEQUATE > PPE (goggles & gloves), as this, too, is hazardous. I think breaking > it by bending actually may require more energy than the disc hitting > something hard with its own edge, but you get the idea...
In the early days CDs were revolving rather slowly (remember the 4x coffee cup holder joke?), so brittle materials were OK. Then drives got much faster, and many were written off by CDs disintegrating in the drive when spun up. So 10-15 years ago the material changed to something tough enough as to be practically unbreakable. You need gorilla hands for more than a few fatigue lines. Well, for the writable ones I tried to break anyway. Volker -- Volker Kuhlmann http://volker.top.geek.nz/ Please do not CC list postings to me. _______________________________________________ Linux-users mailing list [email protected] http://lists.canterbury.ac.nz/mailman/listinfo/linux-users
