# A String of Bucky Balls

1. Jul 24, 2014

### KamakaziX

We have had a heated debate at work and I feel we need to bring in a few outsiders in to help clear things up.

A co-worker of mine believes that if you had a string of bucky balls (small spherical neodymium magnets) held by only the top ball in the chain and allowed to hang such that you could have a string of balls that you would be able to construct "an extremely large number, but not infinite" string of balls (originally he said infinite but then backed down from that statement). He has said that this number is possibly in the thousands or more.

I, however, believe that you would just need enough balls such that the mass of the chain below the first ball would overcome the force between the top two balls in the chain (plus the force from the top 5ish balls or so until the force from the subsequent ball's magnetic field, acting on the top ball, becomes negligible).

Who is more correct? I understand that a lot of this depends greatly on the power of the magnet, but assume that the magnets have a strength 2.1lbs of pull force. Sorry that I can't give you anything more specific I am having trouble determining the strength of the same magnetic balls that we have from manufacturer webpages.

2. Jul 24, 2014

### TheDemx27

Well, it all depends on the space you decide to put the buckyballs in, as that would determine the forces acting on them. Making a few really general assumptions, that we are starting at sea level on earth and that each ball weighs 1 gram. Using F = ma, 2.1 lbs converts to about 9.34 newtons, so we have 9.34 = m * 9.81. Solving for m gives us .950 kg, so you could string 950 buckyballs at the earths surface. From what I've read on the internet the balls have a 5mm diameter so that would be a 4.75 meter string. Rough estimate.