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# Totally Irrevelevant but...

8 replies to this topic

### #1 Ryan 3000

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Posted 06 October 2008 - 02:10 PM

I have become addicted to magnets lately and I decided to buy some. Then I played Halo 2 and found the MAC gun, or Magnetically Accelerated Cannon. I have a theory in my head about how it would work, but I would like to get some math in on this if I could, so I can build one. I want to find out the acceleration of a magnet, with the following information:

A small, cylindrical, 0.05oz magnet with 5 lbs. of push force is in the field of a magnet with 46lbs of pull force. The small magnet is the 'bullet'. In an ideal world, can you tell me what the acceleration would be for the bullet if it was constantly in the repellent field of a larger magnet? Illustration below of how I think this would work:

Tell me you don't want one!!!

Also in case you want the website its very fun to browse, has all the neodymium you'll ever need. They sell to manufacturers of speakers, arts and crafts, and lol Star Trek to stick the transponders to their shirts. Some are powerful enough to turn you into target practice for the loose metal in your home. Others are just fun. http://www.kjmagnetics.com/

Edited by Ryan 3000, 06 October 2008 - 02:22 PM.

No pessimist ever discovered the secrets of the stars, or sailed to an uncharted land.

### #2 ddeerrff

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Posted 06 October 2008 - 04:44 PM

A small, cylindrical, 0.05oz magnet with 5 lbs. of push force

How do you get a magnet to have 'push force'?
Derfram
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### #3 garmanma

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Posted 06 October 2008 - 06:10 PM

Mark

why won't my laptop work?

Having grandkids is God's way of giving you a 2nd chance because you were too busy working your butt off the 1st time around
Do not send me PMs with problems that should be posted in the forums. Keep it in the forums, so everyone benefits

### #4 no one

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Posted 06 October 2008 - 08:43 PM

The real fun starts when you employ a EM field to the mix (although slightly less portable "currently" )
http://science.howstuffworks.com/rail-gun.htm
http://www.popularmechanics.com/technology...aw/4231461.html

"Not everything that counts can be counted, and not everything that can be counted counts."

"Whoever fights monsters should see to it that in the process he does not become a monster"

### #5 ddeerrff

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Posted 06 October 2008 - 10:27 PM

Since a drawning was edited in, back to the OPs original concept.

First, I assume the magnets are oriented N/S (larger magnet) and S/N (smaller magnet). You will need to be able to slide the larger magnet further down than the drawing indicates, or the smaller maget will just stick immediately coaxial to the larger magnet.

Keep in mind that a stonger magnet can totally overpower a smaller magnet. A N pole of a large magnet will obviously attract the S pole of a smaller magnet, but if the strengths are sufficiently different, it might also attrack the N pole. If this happens, that center magnet is going nowhere.

Finally, you will want to be able to slide the larger magnet quickly down to slightly beyond the smaller magnet - and have it hit a hard stop. The repulsion force will work against that stop and a mushy stop will reduce the acceleration.
Derfram
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### #6 Ryan 3000

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Posted 07 October 2008 - 02:07 PM

EDIT: Revising an earlier rushed response. Thanks garmanma and no one for your links. I've studied both rail guns and gauss guns intensely but I believe the most power can be achieved with the most portability, least electricity and least wasted magnetic field in a Ryan cannon. The main thing going for this project is that it's composed of only 4 parts, 2 of which move; and also that it's very light (around 2 pounds, tops). It's possible to reduce to 3 parts, but I need a 'stopper' in the tube so that the slug is held in place and so that I can pull the launcher magnet past it. As for derf, thanks very much for the advice. I've now put that into my plan, and there is room for a 5th part: something to stop the large magnet, as you said. This was all in my head, but you guys have helped me a lot to put this on paper. As for physics, still waiting for someone's help. All I need is the frictionless acceleration. Waiting to strike from above.

Ryan

Edited by Ryan 3000, 07 October 2008 - 05:46 PM.

No pessimist ever discovered the secrets of the stars, or sailed to an uncharted land.

### #7 Ryan 3000

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Posted 08 October 2008 - 05:59 PM

Bump/update!
I've ordered the parts (and some safety things ) and will be building the cannon. Maybe I will make a YouTube video and post here. Guess I won't need physics when I can test the thing eh? Wish me luck.
EDIT: I can't spell

Edited by Ryan 3000, 08 October 2008 - 06:00 PM.

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### #8 ddeerrff

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Posted 08 October 2008 - 06:21 PM

You can start with F=MA, or rearranging A=F/M. You may have the Mass of the projectile, but I don't think you know the force you will get until you actually measure it. Then, as the force drops quickly as the magnets part, you will have to apply a bit of calculus to determine the final 'muzzle' velocity.
Derfram
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### #9 Ryan 3000

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Posted 08 October 2008 - 10:24 PM

I'm sure there's mathematics but... too complex for me. Unpredictable even after mathematics because of the amount of friction you're dealing with.

Edited by Ryan 3000, 08 October 2008 - 10:28 PM.

No pessimist ever discovered the secrets of the stars, or sailed to an uncharted land.

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