# Why do colliding magnets stick intead of colliding elasically?

In my experience, when two macroscopic magnets collide they stick together. That is, they don't collide elastically. When two magnet-shaped masses collide they will emerge from the collision with (approximately) the same energy. Is there an internal mechanism that absorbs the energy? Is it the shape of the magnets?

• It's completely normal that magnets sometimes bounce a little bit - try it. Commented Apr 25, 2021 at 15:45

One of the major differences between colliding steel balls and colliding steel magnets is the energy that goes into deforming the items as they collide.

When steel balls collide, the colliding surfaces become compressed, which results in forces tending to push the balls back apart.

When magnets collide, it is not merely their momentum which causes the collision, but also the attractive force. As a result, in their stable state, there is some compression on their touching surfaces. It is only excess compression that would cause the magnets to tend to push apart.

I don't have experimental data to support this, but I would guess that if magnets were "fired" at each other with sufficiently high velocity, they would "ricochet". However, at lower velocities, they lose too much energy to this surface deformation to ricochet. Perhaps even just throwing the magnets at each other at high enough velocity will work.

• That's it! My major fault lied in ignoring the constant force between the magnets, which indeed isn't there for two colliding pieces of metal. +1 Commented Apr 24, 2021 at 19:31
• Do steel balls dropped on the floor not bounce? Why does two objects being attracted to each other through gravity act differently from two objects being attracted to each other through magnetic forces? Commented Apr 25, 2021 at 3:40
• @Acccumulation Gravity is super weak though. Commented Apr 25, 2021 at 3:43
• For proof that they can bounce off elastically, see this common magnetic toy: youtube.com/watch?v=rMM3ZR8LKgw They bounce off, but then they are still close enough that the magnetic attraction brings them back together, where they bounce again, and this happens many times in a fraction of a second and causes the buzzing noise. Commented Apr 25, 2021 at 3:55
• If you try throwing magnets together, wear safety glasses. It's not rare for them to break violently to pieces because the material is quite fragile.
– jpa
Commented Apr 25, 2021 at 15:53