What happens if you cover up the bottom. Does it float? :D
snip because apparently facepunch is land of the scientific arguments and herp derp i'm wrong
says the guy that got a simple trigonometry question wrong lmao
[QUOTE=scotland1;31450371]says the guy that got a simple trigonometry question wrong lmao[/QUOTE]
hey man i set my calc in radian mode, i goof sometimes
you'd be surprised at how easy it is to fuck up on an easy question just because of "i've done this 20 times, i'm real hot shit" mentality
Yeah our physics teacher did the same demonstration for us except he had one of those tiny but amazingly powerful magnet and it took like six seconds to go through two feet of tubing.
tl;dr on aznz's explanation - The magnet is creating electricity in the copper pipe by losing some of it's downward kinetic energy (meaning it falls slower than it logically should).
[QUOTE=aznz888;31450231]The magnet slowing effect you see is caused by the magnetic fields generated from the neodynium magnets. It creates a dipole attraction as seen here.
[img]http://squidkth.files.wordpress.com/2010/05/dipole_field.jpg[/img]
According to Lenz's law, electromagnetism has energy properties of it's own that must obey Newton's third law, the equal and opposite reaction law. In case you aren't familiar, when magnets move across a piece of copper, electricity is essentially generated from the atoms of the copper. Electricity, as a form of energy, must obey the third law. The electrons try to repel the ends of the magnet, and in short, the magnet tries to repel it back. This is the slowing effect you see.
And if you're tl;dr or "wtf is this nerd shit", go get a goddamn education.[/QUOTE]
What do Newton's laws have to do with this? It's just that the moving magnet induces a current in the copper tube, and that current causes the tube to get its own magnetic field, which slows the magnet down.
At least that's what I remember from highschool-level physics, we did magnetism almost a year ago so I'm a bit rusty on it.
[QUOTE=pebkac;31450871]What do Newton's laws have to do with this? It's just that the moving magnet induces a current in the copper tube, and that current causes the tube to get its own magnetic field, which slows the magnet down.
At least that's what I remember from highschool-level physics, we did magnetism almost a year ago so I'm a bit rusty on it.[/QUOTE]
i may be wrong(high school physics here too) but i believe it's the conservation of energy that causes the repulsion between the tube and the magnet. it's gotta go somewhere.
No it's definitely the eddy currents created in the copper pipe in turn generating their own magnetic fields and repulsing the direction of the magnet. That's how eddy brakes work.
No it's just part of God's plan, it says so in the Bible
So what happens if you put that magnet near two fast spinning copper pipes?
[media]http://www.youtube.com/watch?v=glCNP6qH_Dc&feature=channel_video_title[/media]
[QUOTE=aznz888;31450231]The magnet slowing effect you see is caused by the magnetic fields generated from the neodynium magnets. It creates a dipole attraction as seen here.
[img]http://squidkth.files.wordpress.com/2010/05/dipole_field.jpg[/img]
According to Lenz's law, electromagnetism has energy properties of it's own that must obey Newton's third law, the equal and opposite reaction law. In case you aren't familiar, when magnets move across a piece of copper, electricity is essentially generated from the atoms of the copper. Electricity, as a form of energy, must obey the third law. The electrons try to repel the ends of the magnet, and in short, the magnet tries to repel it back. This is the slowing effect you see.
And if you're tl;dr or "wtf is this nerd shit", go get a goddamn education.[/QUOTE]
Throw out the newton's law bullshit, and explain it with Maxwell's equations, the Lorentz force law, along with Faraday's law of induction, then you'll be correct.
None of this is.
Submerging the copper pipe in liquid nitrogen beforehand vastly increase its conductivity and the strength of the eddy currents. It can take over half a minute for it to float to the bottom of the tube. It's a popular demonstration at my university to impress prospective students :v:
[media]http://www.youtube.com/watch?v=KWnh-Rk-F-8[/media]
[QUOTE=aznz888;31450231]The magnet slowing effect you see is caused by the magnetic fields generated from the neodynium magnets. It creates a dipole attraction as seen here.
[img]http://squidkth.files.wordpress.com/2010/05/dipole_field.jpg[/img]
According to Lenz's law, electromagnetism has energy properties of it's own that must obey Newton's third law, the equal and opposite reaction law. In case you aren't familiar, when magnets move across a piece of copper, electricity is essentially generated from the atoms of the copper. Electricity, as a form of energy, must obey the third law. The electrons try to repel the ends of the magnet, and in short, the magnet tries to repel it back. This is the slowing effect you see.
And if you're tl;dr or "wtf is this nerd shit", go get a goddamn education.[/QUOTE]
You're right on the magnet inducing a current in the pipe, but your link to Newton's 3rd law and about electricity having to obey it because it's a form of energy makes no sense.
The magnet falls through the tube, induces an emf which generates a magnetic field opposing the original one, slowing it down.
[QUOTE=ExplodingGuy;31452108]Throw out the newton's law bullshit, and explain it with Maxwell's equations, the Lorentz force law, along with Faraday's law of induction, then you'll be correct.
None of this is.[/QUOTE]
i don't see what effect maxwell's has on this unless you're pertaining to gauss's law of magnetics, which i assume is common sense(magnets have poles, electrons have charges), unless you want to go with the video quoting Lenz's "An induced current is always in such a direction as to oppose the motion or change causing it" as a result of newton's third.
faraday's is already explained by the fact that magnets generate electricity from it's movement against copper. what's your point?
also fine, i admit i'm wrong, throw out the third law.
[QUOTE=aznz888;31453024]i don't see what effect maxwell's has on this unless you're pertaining to gauss's law of magnetics, which i assume is common sense(magnets have poles, electrons have charges), unless you want to go with the video quoting Lenz's "An induced current is always in such a direction as to oppose the motion or change causing it" as a result of newton's third.
faraday's is already explained by the fact that magnets generate electricity from it's movement against copper. what's your point?
also fine, i admit i'm wrong, throw out the third law.[/QUOTE]
Because he's just trying to act clever.
I understand what you were trying to say.
[editline]31st July 2011[/editline]
[QUOTE=petieng;31452499]
You're right on the magnet inducing a current in the pipe, but your link to Newton's 3rd law and [B]about electricity having to obey it because it's a form of energy makes no sense.[/B]
The magnet falls through the tube, induces an emf which generates a magnetic field opposing the original one, slowing it down.[/QUOTE]
I agree that the bolded part makes no sense. But drawing some parallels with Newton's third law does make some sense.
""An induced current is always in such a direction as to oppose the motion or change causing it""
"To every action there is always an equal and opposite reaction: or the forces of two bodies on each other are always equal and are directed in opposite directions."
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