Magnetic Linear Accelerator ( finding magnets)

[EntryLevelStu]

So i have decided for my physics project to build a magnetic linear accelerator made with half inch ball bearings on a plastic track. The first bearing is rolled and accelerated by the magnet which when struck, launches the ball on the other side due to the momentum of the accelerated bearing. However my problem is which type of magnets should i use? I need something powerful so obviously it should be a Neodymium magnet but I've heard rumors that the magnets mass needs to be about equal the mass of the ball bearings to facilitate easy transfer of energy from the ball striking to the one behind the magnet. Is this true? And can anybody alert me of other pitfalls to watch fro when picking magnets for this project? Thanks for the support.

 

[daveron]

this place is good for magnets http://www.amfmagnetics.com.au/products

You should defantly use neodynium magnets, they have workes great for me.

I was just playing my my linear magnetic accelerator today and I discovered that you would need magnets that are proportional to the ball bearing i used a 1.5cm bearing today on my 0.5 cm magnets and i just woulding work so anything close to the size/mass of the ball would work well as i have used a few other types today as well and aslong as there not to small or to big compared to the size of the magnets it should work well

when you pick magnets if cost is an issue make sure you know how much it will cost you.

hope this helps

 

[Bob S]

You should use neodymium cylinder magnets the same diameter (or cubes the same size) as your ball bearings. In this case, the incoming ball bearing will make contact with the center of the magnet, and produce no torque. The entire impulse will then be transferred to the balls on the other side. See
http://www.hep.princeton.edu/~mcdonald/examples/lin_accel.pdf