What causes a CD to appear to float on a glass surface?

AI Thread Summary
A CD placed on a clean glass surface appears to float due to air being trapped between the smooth surfaces, creating a pressure difference. This pressure prevents easy removal, giving the illusion of floating. The clear coating on the CD contributes to its flatness, enhancing this effect. Over time, the air can escape, causing the CD to eventually touch the glass. The phenomenon is a result of basic physics rather than any vacuum effect.
loststylez
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I know the question sounds a little bit noobish but If you place a CD on a clean glass table seems like the CD is floating. There's vacuum between the CD and the glass stopping you from picking it up yet the CD seems to be floating.
If not I would like to know what other forces could be acting there.
 
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loststylez said:
I know the question sounds a little bit noobish but If you place a CD on a clean glass table seems like the CD is floating. There's vacuum between the CD and the glass stopping you from picking it up yet the CD seems to be floating.
If not I would like to know what other forces could be acting there.

Er... you do know that there's a clear coating on the CD that separates the actual layer from air, don't you?

Zz.
 
I know (I'm a computer geek).. but how's that relevant to the question ?.. except for the fact that it's a near-perfect plane that could enforce my question.
 
There's vacuum between the CD and the glass stopping you from picking it up yet the CD seems to be floating.
If not I would like to know what other forces could be acting there

That's just air being caught between the smooth, very flat surfaces. Since the separation is narrow, the air can only escape (or enter) slowly, and the resulting pressure causes it to seem to float (or 'stick'). The air escapes after a few moments and the CD touches the glass.
 
Thanks, I guess I was thinking too far !
 
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