Quote:
The mass on the left changed it's momentum from 40kgm/s to -40kgm/s. That's a difference of -80kgm/s.


thats why I said

Quote:
the collision generated 160N
80N was used up in stopping the two carts.
80N was used up accelerating the two carts to -40m/s
and +40m/s


Quote:
A change in momentum of only 40kgm/s (1 times) would cause it to stop, not change direction.


but it has a change in momentum of 80N not 40N

so +40N spring tension stops it from going in the (-) direction
and +40N spring tension accelerates it in the (+) direction.

like a spring that stores up +40N
as you apply -40N to compress the spring.
once the spring is compressed and the mass has stopped moving.
you still have +40N stored in the spring.

and that +40N accelerates the 1 kg mass to +40 m/s.

I believe this is where your understanding is flawed.
earlier when you said
Quote:
transfer double it's initial momentum


it cannot double its momentum all by itself.
it would need another force acting on it.

so where is the other force?

Quote:
This is the reason solar sails are supposed to be reflective, not black. Photons bouncing off give twice as much momentum as photons that are absorbed.


just like the spring above!

consider the spring attached to the solar sail.
but the solar sail isnt moving yet.
give the solar sail a mass of 1000000 kg

now apply a -40N force to the spring.
the solar sail feels the -40N force that you apply to the spring , and as you apply the -40N force the solar sails mass resist movement momentarily while you depress the spring.
but you have depressed the spring and if you hold it in with a -40 N force the sail will move away from you.

you can then multiply the
solar sails mass x its velocity

p=mv

and it will equal -40N

that is not double momentum.

that is -40N for -40N

action / reaction

http://upload.wikimedia.org/wikipedia/commons/2/20/Secondlaw.ogg




3/4 inch of dust build up on the moon in 4.527 billion years,LOL and QM is fantasy science.