| Author | Message | ||||||||||||||||||||||
     Grumble |
I experimented for a little while once my order of 20 N40 1/2" magnets came in, and as I kept adding magnets (up to 4) I didn't see a really great increase in velocity for the steel ball. What would be the optimal spacing for the magnets? Perhaps they are too close together? Also, will any of the later magnets in the series be shattered or is 20 in the 'safe zone'? Anyone know what kind of velocity I would get? My aim is to build a relatively fearsome accelerator. -Grumble | ||||||||||||||||||||||
| Simon Quellen Field (Sfield) |
You can't afford enough magnets to get one to shatter in the gauss rifle. You also can't afford enough magnets to become fearsome. The 4 magnet gun throws the ball at about 15 feet per second. A cheap rifle from Kmart throws a slug at about 4,000 feet per second. Each magnet adds energy linearly. If four magnets produce 1 unit of kinetic energy, 16 magnets will produce at most 4 units of kinetic energy. But since kinetic energy is ½ mass times velocity squared, to get twice the velocity, we will need 4 times the energy. Thus 16 magnets will be needed to double the speed, assuming no friction losses, and optimal placement. So, we can complete a table of speeds versus number of magnets:
I would be happy to sell you a quarter million magnets at 3 dollars each. I will need some time to manufacture them, and payment in advance. By the way, if it takes one second to set up the two balls on a magnet, it will take over 3 days to load the gun. If each magnet is 2 inches from the last one, the gun will be over 8 miles long. All of this assumes no friction, and assumes that the optimal distance between magnets is always the same. It seems unlikely to me that 16 magnets will produce twice the velocity of 4. Experiment, and post your results here. This would make a good science fair project. | ||||||||||||||||||||||
| Kevin H Unregistered guest |
Eh-hem...what about the magnets from FORCEFIELD? They have NdFeB magnets up to 2 inches diameter and 1 inch thick. Try http://www.wondermagnets.com/cgi-bin/edatcat/WMSstore.pl?user_action=detail&catalogno=0072 ... I bet one could beat those figures with these magnets!!! | ||||||||||||||||||||||
| Simon Quellen Field (sfield) Senior Member Username: sfield Post Number: 386 Registered: 12-2004 |
Actually, no. The magnets and the balls should be close to the same mass, or you get reflected energy. A billiard ball will hit another and stop, sending the other one on its way. But a BB will just bounce off of a cannonball. This is called an impedance mismatch. The strongest magnets available at this time are the N50's we have in our catalog. When stronger ones are available, we will carry those. We have found that the nickel plated magnets don't hold up to repeated impacts from the balls -- the nickel plating is brittle and flakes off. The gold plating is very soft and malleable, and just gets pounded into the magnet more securely with each impact. The epoxy coated magnets are also prone to the coating flaking off. Besides, your assumption that a bigger magnet will somehow allow you to get around simple arithmetic is unfounded. Even if you could improve on the speed of the four magnet rifle, doubling the speed there still means that you will need 65,536 magnets to get over 3,000 feet per second. And since there are currently only 9 of those $40 magnets in stock, you would do better with our much less expensive magnets anyway. Although I'm sure they'd love to sell you $2,621,440.00 worth of magnets... | ||||||||||||||||||||||
| Jeremy Denton (Unregistered Guest) Unregistered guest Posted From: 64.12.116.130 |
Where can I find 1/2 inch gold plated magnets? I have checked a number of web sites and all I could find were tiny ones. | ||||||||||||||||||||||
| Simon Quellen Field (Sfield) Senior Member Username: Sfield Post Number: 753 Registered: 12-2004 |
Try our catalog. | ||||||||||||||||||||||
| surendra murthy.c (Science_boy) New member Username: Science_boy Post Number: 1 Registered: 6-2007 |
can you sugggest any other high voltage source for the franklin bell experiment. |
