CD shatter if you spin it fast enough

[Erdrick Holmes]

http://www.audioasylum.com/audio/digital/messages/77606.html

Apperently if you spin a CD at about 32,000 RPMs it will shatter in about 1,000 pieces. I saw this happen on TV today but the question is how does spinning a CD make it explode like that?

[edczxcvbnm]

The same concept if you spin something too fast that is on a piece of string...it will eventually break off. The centripital force being applied to the object is too much for it to with stand and it just gets ripped apart.

Its not like plastic is all that strong either and 32,000 is extremely fast. Your engine in your car isn't pushed that hard.

[Yamaneko]

Considering that a car on a freeway going 65mph tends to reach 35,000 RPM tops, I can't see why a CD would not explode.

[eestlinc]

and when would this knowledge ever be useful or pertinent?

[Yamaneko]

Obviously when ninjas are throwing AOL cds at you.

[escobert]

Well if you want to dispose of CDs it may help.

[eestlinc]

so never

and when i need to dispose of a cd I put it in the trash can.

[The Man]

Originally posted by Yamaneko
Obviously when ninjas are throwing AOL cds at you. Gotta watch out for those ninjas. And those AOL CDs. Man, those can be deadly.

[escobert]

But it would be more fun to blow them up. Don't ya think?

[eestlinc]

no

[escobert]

Oh ok. I think it would.

[The Man]

eestlinc knows the score.

[crono_logical]

Hmm, maybe that's why I haven't heard of any drives faster than 52x :p

[DocFrance]

There's also the matter of heat. You see, when a machine is spinning something, this is called shaft work. This shaft work contributes to the energy of the system - the CD, in this case. Because energy is conserved, this shaft work in must be converted to some other energy out (let's see... closed system, non-steady, non-adiabatic, rigid, non-isolated, no change in potential or kinetic energy). So the massive amount of shaft work is converted into the internal energy of the CD - the CD's heat. The CD is heated up by nearly a hundred kilojoules, and promptly explodes, because the CD's component molecules have to much energy to be held together by their normal bonds.

(Thank you, Aero 241)

[Meat Puppet]

Anyone got a picture of somebody who has been spinned so hard they exploded, much like a CD would?

[Marcus]

There was this type of CD-Drive where it happened often, so they removed it from the stores.. Can't remember what type, but I know someone who had a CD explode in his PC. It's not that rare, actually, people started having this problem 2 years ago or sumthing..

[Loony BoB]

If we only talked about useful things in EoFF, this place would be dead.

And I think it'd be pretty cool to see that happen. Hey, I wonder if Sir Krelian could spin that fast...

[Peegee]

I was under the impression that 52x cds tended to break. I have something that *claims* to be 52x but I have no idea if it is. It's definitely not DMA mode, so I doubt it very much.

My DVD writer on the other hand is 4x....which translates to 32 or 48x I think. Anyway, 8x DVD writers definitely are fast (>52x?), but they exist and probably don't break. I don't know :P

[crono_logical]

<div align="justify">http://www.dvddemystified.com/dvdfaq.html#4.2

I notice the CD read speeds don't go above 40x - I guess they realised it was dangerous there :p Since the data is more condense though, it seems you only multiply by 3 to get the equivalent to CD as far as rotational speeds goes :p
</div>

[Erdrick Holmes]

I was wathcing this on Mythbusters on the Discovery channel yesterday and these guys were putting CDs on the ends of cordless drill heads to make them spin at 32,000 RPG and they exploded. They threw a plastic dummy in a glass box to see how much damage an exploding CD can do to a human body, the dummy had a ton of shrapnel embedded in it, it was hillarious.

[Flying Mullet]

Originally posted by DocFrance
There's also the matter of heat. You see, when a machine is spinning something, this is called shaft work. This shaft work contributes to the energy of the system - the CD, in this case. Because energy is conserved, this shaft work in must be converted to some other energy out (let's see... closed system, non-steady, non-adiabatic, rigid, non-isolated, no change in potential or kinetic energy). So the massive amount of shaft work is converted into the internal energy of the CD - the CD's heat. The CD is heated up by nearly a hundred kilojoules, and promptly explodes, because the CD's component molecules have to much energy to be held together by their normal bonds.

(Thank you, Aero 241)
Hee hee hee, he said "shaft work".
http://www.ccs.neu.edu/home/image/images/small-bnb.gif

[Maxico]

Its kinda sad seeing all of this energy put into something as pointless as making a cd explode. I mean the only thing I can see it being usful for is sabotaging pc's. And even then it would be alot more effective to use a virus. As for the question just think of something like one of those weird blue things in childrens play grounds that kids spin on (As its know in the industry) and the way if its going really fast you feel your being pulled out wards. Well at these speeds each partical wil be pulled outwards and they will eventualy give. Well I know people have already said that, but, meh. And you just KNOW that some sick bloke's gonna try it with a hamster.

[Endless]

<a href="http://www.powerlabs.org/cdexplode.htm">Here</a> is everything you want to know AND see about exploding CDs.

[Fuzakeru]

Since when did the ninjas have access to the AOL cds? . . . I thought the pirates had them under their control. >_o
My buddies and I stole like 30 of them once and threw them around the Wal*Mart parking lot. *Sighs* What a life I lead.

. . . . but I wonder. If the CDs are free . . . did we REALLY steal them? Question it . . . XD

[Big D]

Originally posted by Yamaneko
Considering that a car on a freeway going 65mph tends to reach 35,000 RPM tops, I can't see why a CD would not explode. Dang, I'd love to own a car that could do thirty-five <i>thousand</i> RPM. Most cars, even modern sports cars, will red-line at 6,000 or so.

There was once a great commercial where a middle-aged couple load their kids' CD collections into clay-target launchers and then shoot them down with a shotgun. Fun.

[Erdrick Holmes]

I actually talked a friend of mine into blowing up CDs. Were making a box out of glass to contain the shrapnel and put a pumpkin inside to see how much damage it will do. Were attaching the CD to his Roto Zimmer that spins at 80,000 RPMs. Yes, we'll take pictures.

[Chzn8r]

Originally posted by Endless
<a href="http://www.powerlabs.org/cdexplode.htm">Here</a> is everything you want to know AND see about exploding CDs.

That was so awesome!

[Harmless Pigeon]

I like explosions.

[Logan]

I wanna make things explode like that. D:

[Flying Mullet]

The explosions are okay, but I love how the cd has so much power when it's spinning and it keeps running into the door and ramping off of the skateboard over and over and over...

[Proxy]

Originally posted by Big D
Dang, I'd love to own a car that could do thirty-five <i>thousand</i> RPM. Most cars, even modern sports cars, will red-line at 6,000 or so.


I didn't wanna say anything. but i was thinkin "what kind of car does he drive"
and modern sports cars are at about 7 or 8k

and yes, that video was very cool

[Erdrick Holmes]

Well a 52x CD rom drive spins at about 40,000 RPMs so I can see why they would explode after awhile (they can only stand about 32,000 before exploding.)

This is quite possibly one of the best discussions I had ever made.

http://www.smallcave.net/rock/up/Picture%20002.jpg

This is a stack of CDs in my room I found

5 AOL CDs
3 CDs I attempted to burn but I screwed them up
A Sprint Earthlink CD
Disc 1 D (PSX game)
Hardcore 4X4 (Old PSX disc that no longer works)
A few old dos games
And 2 mix CDs that go so horriby scratched

This weekend my friends and I are going to my friend nathens garage and building a device called "AOL's death sentence". Its a table with a hole cut in the middle with a rotozimmer spinning at 180,000 RPMs. We'll stick the zimmer through the hole on the table and cover the zimmer with glass to encase the flying CD shrapnel. We also might put some pumkins and stuff in the glas to see the damage thousands of shrapnel shards do to something that sorta emulates a human skull. Ill take pictures.

[Big D]

You might wanna wear safety goggles, just in case the glass doesn't withstand the impacts and pressure...

"Safety first" is a good rule to remember when you're being wantonly reckless and destructive :D

[Peegee]

hehe "wanton"

pictures are a must. I demand them. I have a huge stack of cds, but I lack the resources to perform such a fun endeavour.

[Red Wizard]

Originally posted by Bert
Well if you want to dispose of CDs it may help. Microwaves are far better at disposing of CDs. *nod*

Anywho, I'd beware ninjas who throw AOL CDs at 32,000 rpm... man, that's make a great low-tech frag-thingy. Talk about real ultimate power.

[The Man]

especially if they're linkin park CDs with pre-sharpened edges to make for more efficient wrist-slashings (http://www.kraptastica.com/vb/). it's probably the best use for linkin park CDs, too.

[Red Wizard]

I've heard they also make for a decent scale-mail for use against dull kitchen knives.

[crono_logical]

Originally posted by Red Wizard
Microwaves are far better at disposing of CDs. *nod*But who wants to dispose of their microwave at the same time? :p

[Red Wizard]

People who would be sent to jail if things on the CDs in question weren't permanently erased.

[The Man]

I've broken CDs in half with my bare hands before; it's not exactly that hard to erase them.

[Red Wizard]

Nah, the FBI can put a shattered CD back together and still get data from it. Microwaving the disc then scuffing the bloody hell out of it is the best way to go.

[The Man]

You can easily just scrape everything off with a pair of scissors then. I've done it before with CD-Rs that didn't burn correctly.

How the hell can someone put a shattered CD back together? The data layer's already falling off of the darn thing.

[Red Wizard]

If they think you've got something that can harm the government (like some encryption algorithms, for example), they're going to do everything they can to prove that you had it and were planning to harm the government with them.

That's as far off topic as I'm going to go, though. My first day back and I'm already hijacking topics. Meh.