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...
To get back on topic, this obviously means that some parts of Linux that
are responsible for keeping the CD in the drive until it has spun down
are actually safety-critical software! Who would have thought that of an
ordinary PC operating system? (Needless to say the computer on which the
above incident happened was running Windows - wouldn't have happened
with Linux! (-: )
Have a safe weekend!
Helmut.
On 16/01/14 20:26, Kent Fredric wrote:
[...]
On a similar note, don't be tempted to place a blank audio optical
disk in a home stereo system, especially one of those AIWA things with
a rotating tray.
It has the fun side effect of picking the disk up, spinning it up,
CONCLUDING THERE IS NO DISK PRESENT AT ALL, then simply dropping it
/without letting it spin down first /, dropping the spinning disk onto
the rotator tray, which may just be enough for the disc to launch
itself off the rotating tray and into the belly of the beast.
Ah, the memories of technology from a bye-gone era.
[...]
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