Basic Straight Line Permanent Magnet Accelerator

[MarcusThatsMe]

TL;DR Summary

Horizontal Permanent Magnet Accelerator Question

I stumbled upon this video on YouTube:



Here is a screenshot with some colored lines added of the part that generated a few questions in my head that I hope some of you smart folk can answer for me.

In the video, the spherical magnet (at the end near the two big magnets) appears to increase in velocity while traveling from left to right, with that in mind my question is:

Is the increase in velocity ONLY due to the larger magnets at the end?

If Yes...

a) Does that mean you could technically remove a number of those smaller magnets (red line)?
b) Do you even need the smaller magnets (red line) to achieve the end velocity, would you really just need a line of middle size magnets (purple line) before the last size (green line)?

If No...

c) Could you technically just create a LONG line of those smaller magnets (red line) and have the spherical ball continuously increase in velocity if going in a straight horizontal line?

Last question...

I know that as the spherical ball passes each set of magnets it has to enter and leave those magnetic fields (which is why I believe railguns use magnets you can turn on and off so you don't have to deal with leaving the field, you just make it disappear as the next field turns on, but I want to focus on permanent magnets), would it be more useful to place them closer together or to ditch the circular magnets for rectangle or square magnets.

My kids liked the video, so we were thinking of replicating it while trying to increase the velocity, however, it would be great to replicate in a more efficient manner if there is one utilizing permanent magnets.

Thanks in advance!

 

[mfb]

Neglecting differences in friction you could remove everything apart from the last few magnets and release the ball closer to them.

c) Could you technically just create a LONG line of those smaller magnets (red line) and have the spherical ball continuously increase in velocity if going in a straight horizontal line?

No. This is directly clear from conservation of energy.

Railguns don't use permanent magnets at all, they use a high current going through the rails and the projectile (or a sled carrying that projectile). The closest equivalent would be a coilgun which - as the name suggests - uses coils that can be turned on and off to keep accelerating the projectile.

 

[MarcusThatsMe]

Neglecting differences in friction you could remove everything apart from the last few magnets and release the ball closer to them.

That's what I was thinking.

This is directly clear from conservation of energy.

That's logical.

Railguns don't use permanent magnets at all, they use a high current going through the rails and the projectile (or a sled carrying that projectile). The closest equivalent would be a coilgun which - as the name suggests - uses coils that can be turned on and off to keep accelerating the projectile.

That was sort of my limited understand. Each coil would activate to pull the projectile then the previous coil would deactivate to release the magnetic hold and the next would activate to accelerate/pull it ahead until eventually its just released from the final coil at a high velocity.

I appreciate your response!

 

[Cutter Ketch]

TL;DR Summary: Horizontal Permanent Magnet Accelerator Question

Is the increase in velocity ONLY due to the larger magnets at the end?

Mentioning for completeness: there is also acceleration falling into the first of the small magnets as he demonstrates at the beginning of the video. But then there is no further net acceleration going from small magnet to small magnet along the rail. Nevertheless, I think it looks pretty neat to coast along a long rail before doing the real business at the end.