Shorting speaker terminals

[safebet]

Actually, the electrons themselves travel very slowly. It is the bump from electron to electron that moves at near the speed of light.

Yes. Effect is near speed of light, actual electrons move only minimally. Something like this.

 

[Mr Boochie]

I'm hanging with @rothwellaudio here ..

It's pure physics ..
A coil moving in a magnetic field generates current and vice versa ..
Wiring the terminals together creates the conditions for both ..
Can't spin forwards and backwards simultaneously .. so it remains at rest ..

Essentially using the EMF as a brake ..

It's a mass suspended on a spring inside that coil so a big enough whump could probably still make it hit the stops ... but it isn't going to bounce and hit twice ..

The compliance of the speaker also helps to control the redundant movement.