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When Spun Really Fast, CDs Explode
Anonymous Coward writes: "Ever wonder why cd-rom/cd-rw drives are not getting any faster? Wonder why they heat up? This page has a rather amusing experiment where they put various CD's into something that can spin up to 30,000RPM and found that most cd's explode at just around 28,000RPM. Oh and they seem to like using Corel CD-ROM discs for their experiment." Update: Yep, it's a dupe...
Don't those 52X ones have multiple read heads so they don't actually have to spin that fast?
also you can always just put more data on the disk. I mean maybe you could never read a 100GB disk faster than 52X, but thats still like 100GB of data read in a minute or two
Maybe if they spun the laser it would be faster, since the disk seems to have more mass. Or better yet the spin the laser in the other direction of the disk so they are both spining.
-James
The article talks about constant linear velocity (used in the original audio standard) and constant angular velocity drives. It comments how manufacturers like to have CAV drives to quote impressive speeds compared to the CD (audio) standard, but doesn't mention a much more important reason for using CAV: if you used CLV you'd need to wait for a long time (probably seconds) for the spin rate to change and stabalize whenever you seeked from one part of the disk to another.
Quattuor res in hoc mundo sanctae sunt: libri, liberi, libertas et liberalitas.
Contrary to popular belief, plastic doesn't last forever.
:)
Since CD is made up of two layers of clear plastic, sandwitching a thin wafer of metal media inside, the more the CD is aged, the weaker the plastics of the CD become.
And so, the maximum spinning speed for a CD depends on how old the CD is.
I do have some pretty old CDs from the early 80's, and I will NOT put them in my 52X CDROM drive. Unless of course, I want to scrap bits and pieces out of my machine.
Aw, fuck it. Let's go bowling. - The Big Lebowski
It really would be a good idea to ban compact discs from airline flights (if they're going to go so far as to ban things like nail clippers and eye glasse screw drivers). A CD can be broken into two pieces very easily and are still strong enough that either piece could be used to slash someone's throat, wrist, belly.
VERY dangerous.
I don't know about that...
I do know that I had some fun with an old 5 1/4" Full Height HDD and a 3-phase grinder once.
Did you know that you can spin hard drives like that up fast enough (mostly safely) to actually make the centripetal force cause the drive to stand up on a corner for a bit! FUN FUN FUN! More fun than jumping off a moving bike to see how far it will go before it falls over (or hits something). Even more fun than trying to roll a quarter completely down the college hallway during late hours!
(and no, even with the stress the grinder put on the platters and the high speeds nothing "exploded"... but someone did mention to me I should have worn protective gear anyways.)
If you could be told what you can see or read, then it follows that you could be told what to say or think - BoC
Yes, it does. You'd think it wouldn't - you can tell whether you're spinning or not without any reference to the rest of the universe by the forces on your body (central forces required to keep you from flying apart).
But, if you work through the equations of general relativity for a universe rotating around a fixed body, you'll find that the motions of those distant galaxies generate forces on the body - outward forces exactly balancing the centripetal ones!
So a spinning CD is exactly equivalent to a fixed CD with the universe spinning around it - no experiment can tell them apart.
Yup, if you spin the universe fast enough around the CD, you will cause it explode. That would be a good party trick, but there are certain practical difficulties involved in getting the entire universe to spin.
Besides which, because the CD spinning and the universe staying still is exactly equivalent to the universe spinning and the CD staying still, everybody would just think you were spinning the CD anyway.
I found a non-overclocked dremel will easily cause the cd's outer tracks to skew. Extreme vibration will be the result as the cd warps quickly. Speed will drop quickly due to this imbalance. Solution: turn up the power!
I wonder what would happen if you used a heat gun to soften up the outer tracks as it spins fast. I wonder if these CDs would stretch to the size of pizza dishes (extremely warped dishes of course). Since you've already got the spinner made, you only need a $25 heat gun.
"Face it, a nation that maintains a 72% approval rating on George W. Bush is a nation with a very loose grip on reality.
We've had two CDs go in the last 6 months in my office, both in 50x drives. One was a CDR, the other was an original photoshop CD. In both cases bits flew out of the front of the drive, and they didn't half make a noise! One of the drives work afterwards, despite having bits of plastic knocked off by the exploding disc.
Dangerous if you ask me - if you have a tower case, make sure the CD drive isn't at eye level!
A fun experiment is to put a polished, hardened steel rod through the spindle hole, then hit it with a jet of compressed air. If you get the bearing effect just right the CD will spin up to a 10-20krpm and will occasionally disintegrate on the spindle. Mostly though if you let it slip off the spindle it'll hit the ground, stand due to gyroscope effect while the edge melts against the ground enough to get traction, then take off across the room and explode on impact with the opposite wall.
You can also make an air bearing with an orange by cupping your hand just right and blowing compressed air between your hand and the orange. Oranges explode good.
We had one poor lady in our office who was trying to
install a feature of MS Office from her CD-ROM. She stuck the thing in and after about 5 seconds there was a loud bang from the computer. She nearly hit the ceiling when she jumped.
After checking signs of smoke and what not, we opened the CD tray and there was nothing but a shards. It had completely disintegrated into pieces no more than a couple cenitmeters long.
Of course the drive was completely hosed after that. It just made a jingling noise with all the shards in the unit.
Yet another fine M$ product - exploding CD's.
It is possible for a point to be wrong, flat out.
for instance:(these are just examples, because I don't want to dig up the article)
Linux doesn't have any graphical interface.
No company has ever released a game for Linux.
Not one piece of Windows software runs well enough under WINE to consider using day-to-day.(rather subjective -- until you see that some programs run identically to their windows counterparts, such as Quake II, which makes this flat-out wrong.)
Linux users are forced to use Netscape 4 if they want to surf the internet.
Linux has no way of changing the IP address of an interface without resorting to the command prompt.
No company would ever consider deploying Linux.
No hardware company would ever release drivers for Linux.
If I recall, he did make points such as the above(not the exact ones, mind you). There's nothing subjective about saying "$X doesn't exist under linux", or "linux doesn't have $Y", when it does exist. Saying "I don't like $Z" is a completely different matter...
It's been a long time.
1)The vast majority of statements imply the usage of linux as a platform. Therefore, it is generally good form to accept the common usage.
2)Quake is a game which was released under linux. So are Quake III and UT(the former as a boxed item one could buy off the store shelf sans windows version). You'd have to get pretty narrow on your definition of "game" to subjectively say that no company has ever released a game for it. In such a case, the new, narrower definition of "game" would allow the new statement to be correct, but the sweeping generalization "no company has ever released a game for Linux" remains incorrect.
3)dosemu used to be a biatch to install, I'll admit that, but because you didn't use it, you can't subjectively or objectively say anything about it's functionality as a DOS emulator, merely that you failed to install it. Objectively, the program emulates DOS well enough to run those games, regardless of your own experiences trying to install it.
4)Narrowing the field to only mainstream software, both Opera and later versions of netscape are available. Objectively, there's nothing stopping an individual from using non-mainstream software in terms of functionallity, so in this case, it's not the linux platform which is forcing the user to use netscape 4, but their own stubbornness. Once again, narrowing the definition makes the new statement correct, but the original sweeping "users are forced to use netscape 4" statement is still false.
5)and I grimace because I mentioned that these were mere examples. This very example came up yesterday in a chat I was having regarding the user freindlyness of linux. Sometimes trying to use an OS means spending five minutes just clicking around the interface just exploring, but that's another matter.
6)Just another example. One that many people like the echo. You'd be suprised how many people(on slashdot) believe that no company would ever consider using linux as either a back-end or a desktop. This is, of course, wrong. Short of narrowing the definition(which makes that narrow definition correct, but the original statement still false), companies and governments the world over are considering Linux.
7) I think you'd be suprised at the number of companies which are releasing drivers. Many winmodems have drivers for Linux now for instance.(oddly enough, my rockwell modem works far better under Linux than under Windows, as does my Geforce 4)
8) the subjectivity of the language doesn't mean that vast overgeneralizations are correct when they are narrowed later.
It's been a long time.