What magnetism tests have been done?

[Fester]

I did some experimentation recently. I rigged up magnets with some duct tape to try and get an idea of force required for  separation  of magnets attracted at the face.
I used 1/4" by 1/8" disc magnets I purchased at Hobby Lobby. By using a sport drink bottle and water, 2 magnets attracted together required approx 20 oz of water to separate them. Next i tried the same fixed magnet but this time taped 2 magnets together in attraction to test for separation force. 2 magnets vs 1 magnet came out to 30 oz of water.
Now 20 oz of water is 591.58 grams and 30 oz is 887.22 grams. The sports drink bottle with tape is 40 grams. So 1 magnets was 639.58 grams and 2 magnets was 927.22 grams.

Now in effect by doubling the magnets the force required to escape did not double. 927.22 - 639.58 = 287.64. with a second magnet i added less than half of the original weight it needed to break a 1 on 1 magnet hold. My kitchen sink rig will not support a 3 magnet set up. I will actually need to construct something for the purposes of charting the mass needed to break the pull. i am hoping the diminishing return effect continues, to the point where a device could be build to abuse this property. The downside is using water when the system breaks free, it tends to slosh around while attempting to catch the container. If this continues I will have to measure them in an offset manner( like a staircase) as well, trying to get same side polarity to stick out for a chain pull. And then measure end forces.

3 variables are key to any design. Mass, Velocity, and breaking force. the kenetic energy equation has all of these built in. E sub k= 1/2 (M x Vsquared). And trying to get E sub k greater than the breaking force. If the magnets have diminishing returns, then the longer the track the more velocity and at somepoint velocity should eclipse the barrier in linear motion.

Does anyone else out there have raw data like this? Or maybe point me to a websitre that has the data?

[Cloxxki]

It sorta makes sense, the second magnet has a larger distance to the opposing one. Or, perhaps more accurate, the heart of the 2-stacked magnets is further away than it was with one.

If you'd use one wide magnet on one side, and mulpiple small ones side by side against it, your mileage might vary.

[d3x0r]

I might assert that you have to measure from the center of the magnetic masses rather than the faces... since the 1/r^2 falloff is technically from the center of (mass/charge/magnetic moment)?
And while you're at it, if you can confirm/deny that magnetic attraction is stronger than repulsion ( http://www.youtube.com/watch?v=8sUpFc-0yg0 ) would be great

[Fester]

Lets not jump too far ahead:D Attraction and repulsion is actually acceleration and deceleration. As a magnet approaches opposite pole, it goes from a weaker field to a stronger one and accelerates. Then it hits the sticky spot and decelerates as the opposed poles try to attract the object moving past. Most OU builds are done this way with attraction faces coming together. The difference is they actually dont touch as my testing is doing. So the force required to break the hold is actually less. So my 640 grams for a single magnet contacted with another magnet, using gravity, is quite a bit of joules when calculated. But non touching is less force. So with the same 640 gram mass ( if the magnets can pull it), would require less velocity, since the breaking force is lowered. In reality trying to get a stator to speed up to 9.8 m/second^2 is not an easy feat to match the same velocity of gravity.

As for measuring from center I have 24 -1/4 by 1/8 inch magnets if you line that many up in one big stack and put a magnet in the center(on the side of the cylinder), it takes almost no force to separate the magnet at the center compared to the ends. After i do all my end tests, I can try the same set up but breaking the center of the stack.
I would have to theorize the diminishing return of weight is actually due to the fact the magnets are not 1 magnet. The faces being attracted to each other are actually reducing the over all force of the ends. Basically it takes some energy from the overall system to keep the stack together. the only application i could see resulting from my tests is a stack that attaches and then releases because  it could not support its own weight once energy it lost from the contact in forming a "new system". And I fear what such a device would actually do to the magnet since attaching is very close to impacting. And we all know how bad that is for magnets. Mind you this is all speculative till I get some more numbers done.

As for testing repulsion. The only rig I can think of would be a tube with a magnet( tube sitting vertically). And another tube introduced inside the first. With a magnet in repulsion inside of it. Both being fixed to their respective tube. the second tube could have a large container, for adding wet sand for example. Piling it up till the magnets contact. then measure the volume of its sand and calculate its weight. This would act much like compressing a spring.

[d3x0r]

Okay then the other bit of trivia I can add... (and ya I'm probably missing the ballpark entirely if where you're actually at)

while playing with the green magnetic field paper, there is a 'bubble' at the ends of the magnets, and if your magnets are smaller than this bubble, then adding more magnets will increase that strength, but more internally are diminishing returns...   Hmm I don't have great illustrations of this but

This is a 1"diamget by 1/4"high cylinder magnet on its edge
https://www.facebook.com/photo.php?fbid=219204778100955&set=a.210482342306532.52736.100000343030096&type=3
This is the field on it which extends about the same as the radius of the magnet, if I therefore stack 5 together then they really stop contributing to the end field...
https://www.facebook.com/photo.php?fbid=219204634767636&set=a.210482342306532.52736.100000343030096&type=3