# Thread: Perfectly elastic relativistic collision

1. # In a perfectly elastic relativistic collision, which one of the following quantities is not conserved:
a)Momentum
b)Energy
c)Rest mass
d)Angular momentum
In non relativistic elastic collisions, energy and momentum will be conserved. But I don’t know about relativistic elastic collisions. Could anyone please explain? Can we apply the Newtonian concepts in these cases? Suppose the collision is inelastic (relativistic), then which quantity will be conserved?

2.

3. The sum of all of the 4-momentum vectors is conserved, which implies conservation of relativistic energy and momentum. Rest mass is also conserved, along with angular momentum. The only quantity that isnt conserved is observed mass of each object.

(p.s.- This has shown with experiments to be accurate, and i dont want to hear anything martillo has to say about it.)

4. yepp, its right. The mass isnt conserved becuase the energy for each object can chance and when that changes mass changes aswell

5. Originally Posted by Vroomfondel
The sum of all of the 4-momentum vectors is conserved, which implies conservation of relativistic energy and momentum. Rest mass is also conserved, along with angular momentum. The only quantity that isnt conserved is observed mass of each object.

(p.s.- This has shown with experiments to be accurate, and i dont want to hear anything martillo has to say about it.)
Do u mean that all the 4 alternatives are conserved? Are these conserved in the case of inelastic relativistic collisions also?

6. Originally Posted by photon
Do u mean that all the 4 alternatives are conserved? Are these conserved in the case of inelastic relativistic collisions also?
4 alternatives? Do you know what the 4-momentum vector is? http://en.wikipedia.org/wiki/4-Momentum. That should explain everything.

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