The physics of rattler magnets

[jetwaterluffy]

The physics of "rattler" magnets

I have been playing around with these magnets (mine are 5.5cm long, 1.5cm diameter at the central bulge), and some of the effects I am not quite sure how they work, although I have some ideas. These are the effects:
First, their actual function, the "rattle" noise they make when you throw them together. However, when you throw one of them at something, metal it makes no such noise, just the ordinary noise of metal on metal. I think perhaps the magnets are both spinning, so switch from repelling to attracting to repelling again, which causes them to bang together repetitively, causing the noise.
When I put the magnet perpendicular to the chair leg at the top, it slides down, while swiveling back and forth. When I put it parallel, it stays where it is. The effect is especially pronounced when I tilt the chair leg 45°. Initially I thought that it was due to magnetising the chair leg, but now I think perhaps it is due to it being attracted to the same direction as the chair leg, and when it isn't in the same direction, the magnetic force is weaker, so it falls down some more.
When I stack 2 of these chair legs together, so the magnet kept is between the top of the two chair legs, and the chair legs come closer together as you go down, then if the magnet is spun, it spins and goes down the chair legs really fast and doesn't appear to slow down. I set it so the chair legs can move to accommodate for the movement of the magnet. If I don't, it still spins and goes down really fast, but it falls off the chair legs. I think perhaps it works in a simerlar way to a ball rolling down a hill, but I'm not sure.
Do you have any explanations, and are any of my ideas right?

 

[eljose79]

Hello,

Thank you for sharing your observations about "rattler" magnets. I find these types of phenomena very interesting and would love to offer some explanations based on my understanding of physics.

First, let's discuss the "rattle" noise that these magnets make when thrown together. You are correct in your assumption that the magnets are spinning when they collide, which causes them to switch from repelling to attracting to repelling again. This repetitive motion creates the rattling sound as the magnets continue to collide with each other.

Regarding the magnet's behavior on the chair leg, your initial thought of magnetizing the chair leg is not entirely incorrect. When you place the magnet perpendicular to the chair leg, it is attracted to the same direction as the chair leg, as you mentioned. However, when it is parallel, the magnetic force is not as strong, so the magnet is not as attracted to the chair leg and can easily slide down. This is due to the magnetic field being strongest at the ends of the magnet, so when it is parallel to the chair leg, the magnetic field is not aligned with the chair leg's direction.

Lastly, let's discuss the stacking of the two chair legs and the magnet's behavior. This is similar to your previous explanation of a ball rolling down a hill. The spinning motion of the magnet creates a force that propels it down the inclined plane formed by the two chair legs. As you mentioned, if the chair legs are fixed, the magnet will eventually fall off due to the decrease in the inclined plane's angle. However, if the chair legs are allowed to move, the angle remains constant, and the magnet can continue to spin and move down the legs at a constant speed.

I hope this helps to clarify some of your observations. Keep exploring and experimenting, as there is always something new to discover in the world of physics. Thank you for your contribution to the discussion on "rattler" magnets.