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What Happens When You Drop A Magnet Inside A Copper Tube [video]

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Re: What Happens When You Drop A Magnet Inside A Copper Tube [video]

#91

Post by jonnathanson »

noir_lord wrote: post #56
malandrew wrote: post #48

Earlier quoted context omitted.

That's it? I was under the impression that copper was far more expensive and is the reason why expresso machines are as expensive as they are.

Copper compared to many metals isn't particular expensive per KG, it is just relatively expensive in the class of metals that we use a crapload of (for example aluminimum is around $1.8 per KG) it is still much cheaper than tin at ~$22. The main reason that copper is so valuable is it has so many uses and is very easily recycled(I saw an estimate that said 80% of all the copper ever mined is still in use) so holds it…

This.

Copper is always in demand, has a bajillion uses, and can be scrapped and reworked very easily. This is why you hear about meth heads stripping copper wiring out of old homes. It's not that the copper is incredibly precious. It's that the copper is so easily liquefied into cash at any number of one-stop, no-questions-asked destinations.

Copper is expensive as a building or product material, not in and of itself, but in relation to many of the alternatives in any given application. Small differences in component costs, scaled over large supply chains, add up to huge differences in margin at the macro level.

Re: What Happens When You Drop A Magnet Inside A Copper Tube [video]

#92

Post by taliesinb »

Crito wrote: post #35
sillysaurus2 wrote: post #32

Earlier quoted context omitted.

Could this be used as a kind of elevator tech? I'd love to ride one of these down a gigantic copper tube. It'd be completely impractical, of course, but a whole lot of fun.

You could probably use eddy-current brakes as a safety system for elevators. Many roller coasters use eddy-current brakes. It would take a hell of a lot of magnets to strap to a person to allow them to jump down a copper pipe though.

Another fun example of braking are the electrodynamic tethers [1], in which you (a satellite) are the copper tube and the entire earth is the magnet!

[1] http://en.wikipedia.org/wiki/Electrodynamic_tether

Re: What Happens When You Drop A Magnet Inside A Copper Tube [video]

#94

Post by e12e »

Crito wrote: post #35
sillysaurus2 wrote: post #32

Earlier quoted context omitted.

Could this be used as a kind of elevator tech? I'd love to ride one of these down a gigantic copper tube. It'd be completely impractical, of course, but a whole lot of fun.

You could probably use eddy-current brakes as a safety system for elevators. Many roller coasters use eddy-current brakes. It would take a hell of a lot of magnets to strap to a person to allow them to jump down a copper pipe though.

But it's possible to the same experiment with a battery and an electro-magnet, isn't it? (Not sure how the power-density of lithium-ion batteries would relate to floating 80 kgs down a tube... but seeing as people have demonstrated hover-boards, it should be doable) ? Assuming the purpose is a) float down tube, and b) SCIENCE! -- and not c) with rare earth magnets...

Re: What Happens When You Drop A Magnet Inside A Copper Tube [video]

#95

Post by e12e »

cincinnatus wrote: post #78
baq wrote: post #4

be very careful when handling such powerful magnets - if you have something metalic on you, they might jump off the table and smack you really hard. bones will be broken.

And if you have little kids treat them like guns. Lock them up when you aren't around.

Always good to lock up your kids when you aren't around. ;)

Re: What Happens When You Drop A Magnet Inside A Copper Tube [video]

#96

Post by e12e »

aaronsnoswell wrote: post #26
malandrew wrote: post #8

I can only begin to imagine how much a piece of copper tubing that thick costs. That's a lot of copper.

The effect works just fine with thinner tubes and smaller magnets - I've done it using 15mm 'plumbing' copper pipes.

Should work with a paper tube and copper wire as well? [edit: not saying that would be cheaper and/or easier, just that it should be possible...]

[edit2: A stripped wire, that is - not one with insulation -- which would be more suitable for making a spool]

Re: What Happens When You Drop A Magnet Inside A Copper Tube [video]

#97

Post by peter_l_downs »

aunty_helen wrote: post #82
dublinben wrote: post #40

Original link: https://www.youtube.com/watch?v=keMpUaoA3Tg This digg page is blogspam.

The problem with the youtube link however is that any video with 'magnet' in the title brings you uncomfortably close to thousands of youtube nutters posting about perpetual motion machines.

s/problem/feature

Re: What Happens When You Drop A Magnet Inside A Copper Tube [video]

#99

Post by noonespecial »

adsr wrote: post #27
malandrew wrote: post #8

I can only begin to imagine how much a piece of copper tubing that thick costs. That's a lot of copper.

A kg is about $7 at the moment it seems, so suppose that's 5 kg then $35.

A quick browse over at onlinemetals leads me to believe that you're probably off by a factor of 10x-20x.

http://www.onlinemetals.com/merchant.cfm?id=1288&step=2&top_...

Re: What Happens When You Drop A Magnet Inside A Copper Tube [video]

#100

Post by tedsanders »

Shish2k wrote: post #41
tedsanders wrote: post #25

Earlier quoted context omitted.

No. Because copper isn't ferromagnetic, it will not be magnetized by the magnet, and consequently the magnet and the copper will not be attracted to each other. (In fact copper is diamagnetic, so it will actually slightly repel.) Source: I am a magnet scientist.

> I am a magnet scientist. Judging entirely by the name, that sounds awesome :D What do you do all day?

A lot of reading, plumbing, and electrical work. But when things are running smoothly, we grow complex oxide crystals using pulsed laser deposition and then measure their magnetism with SQUIDs (superconducting quantum interference devices).
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