Cam somebody explain the physics behind this trick?

[Pepsi90919]

Originally posted by: aplefka
That's effing nuts. The ad I got was weird too.

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well, don't you?

 

[0roo0roo]

Originally posted by: mobobuff

Originally posted by: 0roo0roo
yea heatsinking.
steel wool burns cuz its increased surface area. block of steel has too much heatsinking to burn

Your post reminded me of this video. There are other videos with more action, but this one has Johnny Cash.

Yaaaay!

hah

 

[destrekor]

Originally posted by: mobobuff

Originally posted by: Agentbolt

Originally posted by: JackBurton

Originally posted by: gururu2
the cup has to be weighted with water for proper support. the weight of the forks is distributed and highest at the ends of the forks due to the curvature. the toothpick just serves as a displaced fulcrum. the toothpick has nothing to do with counterbalancing the weight.

Exactly. I didn't even think it was a good "trick." After he burned the toothpick I was saying, "Yeah, and?"

It's not supposed to be a fucking magic trick, it just looks cool to 99.9999% of people out there who don't have to pick apart something that looks vaguely neat with nerdy physics.

You can't expect a forum full of nerds to not pick apart the trick with logic. Logic makes them comfortable, and it irritates them when others do not understand something that seems so simple to them.

Still I think the trick is cooler when used with two toothpicks, one horizontal and one verticle. A slowly burning toothpick just takes focus away from the really cool part.

hit the nail on the head (totally had that written as head on the nail, lmao)

i'm that way, depending on the scenario.
i have a love/hate relationship with 'magic' shows. I love watching them, because it drives my mind crazy. But I also hate them, because I can never figure out how the hell somebody does something, and will dwell on it for awhile trying to apply logic to it in order to understand it. never works though. damn showmen.
i also, when something is seemingly simple to me, get frustrated when I can't get someone to understand. Such as with computers and my parents inability to operate them. :laugh:

 

[soydios]

i'm not sure that the fire would stop at that exact point on the toothpick, but the balancing is real, because the center of gravity of the forks is on the rim. same principle as this: http://www.physics.brown.edu/p...lids/demos/1j2022.html

 

[jagec]

Originally posted by: Agentbolt
It's not supposed to be a fucking magic trick, it just looks cool to 99.9999% of people out there who don't have to pick apart something that looks vaguely neat with nerdy physics.

Topic Title: Cam somebody explain the physics behind this trick?

Umm...

Originally posted by: 91TTZ

Originally posted by: MrPickins

Originally posted by: Argo
The part I don't get is why did the toothpick stop burning exactly at the edge of the glass?

The cup acts as a heatsink. Take the heat out of the reaction, and it can no longer sustain itself.

That's not why. It wasn't burning very well to begin with, and when it got to the cup it couldn't get enough oxygen from underneath. Stainless steel has poor thermal conductivity anyway.

Still much better than air...but I agree, the lack of oxygen was the real reason why it went out.

 

[Eeezee]

Stainless Steel is not a good conductor and would not make a good heatsink. You might be able to make this claim if the cup were made of silver or aluminum (or copper, but that cup sure a shell isn't copper).

Ultimately, there's not enough oxygen at the rim of the cup to keep the reaction going. The heat sink aspect is definitely real, but its effect is negligible.

 

[BrownTown]

Originally posted by: Eeezee
Stainless Steel is not a good conductor and would not make a good heatsink. You might be able to make this claim if the cup were made of silver or aluminum (or copper, but that cup sure a shell isn't copper).

Ultimately, there's not enough oxygen at the rim of the cup to keep the reaction going. The heat sink aspect is definitely real, but its effect is negligible.

I'm not 100% sure as to the cause of the fire burning however saying that stainless steel is not a good heat sink is just silly, sure its not the very best of anything, but thermal conductivities range over several orders of magnitude. A quick look at wikipedia shows that stainless steals thermal conductivity is 600 times that of air and while it might only be a fraction of some other metals it is still a very good conductor of heat.

 

[maziwanka]

Originally posted by: MrPickins

Originally posted by: Mrvile
You guys never had those toy birds that would balance on your finger by the beak and "float" in the air?

I had forgotten about those.

http://physics.bu.edu/~duffy/mech/1J20_46.html

great reference

 

[Agentbolt]

Originally posted by: jagec

Originally posted by: Agentbolt
It's not supposed to be a fucking magic trick, it just looks cool to 99.9999% of people out there who don't have to pick apart something that looks vaguely neat with nerdy physics.

Topic Title: Cam somebody explain the physics behind this trick?

Umm...

Originally posted by: 91TTZ

Originally posted by: MrPickins

Originally posted by: Argo
The part I don't get is why did the toothpick stop burning exactly at the edge of the glass?

The cup acts as a heatsink. Take the heat out of the reaction, and it can no longer sustain itself.

That's not why. It wasn't burning very well to begin with, and when it got to the cup it couldn't get enough oxygen from underneath. Stainless steel has poor thermal conductivity anyway.

Still much better than air...but I agree, the lack of oxygen was the real reason why it went out.

I'm not referring to the OP, I'm referring to the people whose reaction was "Yes, and?" because they understood the physics behind it, and were acting like this was supposed to be some stunning magic trick. It's a cheap, easy gag to do at parties, that's it. The unwashed masses are not going to immediately think "Well that's lame he's just demonstrating that when an system's center of mass is below the point of suspension the system is in equilibrium", they're going to think "Hey that looks kinda neat"

 

[n7]

Nice.