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max8166
2007-Aug-25, 07:39 PM
Question:

When pair production (http://en.wikipedia.org/wiki/Pair_production) of protons occur, kinetic energy is transformed into the mass of a proton/anti-proton pair.
I would assume that you could work out the numbers by using E=MC^2 and so, (unlike billiard balls whose total speed would be a sum of the initial speed) the resultant speed of the particles produced would not sum to the speed of the original particle.
http://www.local-web-pubs.co.uk/app/pp.gif
If the collision occurred within a space ship, the original proton ion would create a backward force on the ship when fired from the accelerator (as a normal ION Drive (http://en.wikipedia.org/wiki/Ion_drive) works) but would an equal and opposite reaction occur at the point of matter creation?

Ken G
2007-Aug-25, 09:19 PM
Yes, momentum is conserved in matter creation.

Albert
2007-Aug-25, 09:27 PM
What do you mean by "an equal and opposite reaction" ?

trinitree88
2007-Aug-25, 10:27 PM
Yes, momentum is conserved in matter creation.

KenG Agreed. Momentum is always conserved in all particle interactions: linear momentum, and angular momentum...part of the hierarchy of conservation laws.
pete

max8166
2007-Aug-28, 08:28 AM
Seems I was forgetting that the initial collision does not create the anti atoms, The Momentum is conserved as the collision makes the pair involved in the collision get extremely hot. The Anti matter is then a by product of this extreme heat.

What do you mean by "an equal and opposite reaction" ?

The Law of the conservation of Momentum states that for every action there will always be an equal and opposite reaction. In the above example the thrust of the particle being fired from the particle accelerator is equal to the thrust of the the target being forced backwards from the recoil of the impact.
Wiki Momentum (http://en.wikipedia.org/wiki/Conservation_of_momentum)

trinitree88
2007-Aug-28, 07:42 PM
Seems I was forgetting that the initial collision does not create the anti atoms, The Momentum is conserved as the collision makes the pair involved in the collision get extremely hot. The Anti matter is then a by product of this extreme heat.

The Law of the conservation of Momentum states that for every action there will always be an equal and opposite reaction. In the above example the thrust of the particle being fired from the particle accelerator is equal to the thrust of the the target being forced backwards from the recoil of the impact.
Wiki Momentum (http://en.wikipedia.org/wiki/Conservation_of_momentum)

Max. Careful with your phrasing there. The momentum of the particle fired from the accelerator is exactly equal to, and opposite in sign to the accelerator itself....that's where the forces occur in pairs, too. Whether the collision is elastic, or inelastic at the target, the total momentum of the incoming particle, and the target (at rest, zero)...is conserved. But in an inelastic collision...say the incoming particle sticks to the target...the recoil of the target itself does not carry it all away, part of it is carried by the particle there...

pete.