# Relativistic particles

1. May 11, 2009

### martyf

1. The problem statement, all variables and given/known data

A relativistic particle with mass at rest M0 and velocity v hits another particle with mass at rest M1. the collision is perfectly inelastic. How can I calculate the mass at rest of the new particles after the collision?

2. Relevant equations

3. The attempt at a solution

2. May 11, 2009

### nickjer

Conservation of momentum and total energy.

3. May 11, 2009

### Cyosis

Easiest way to do this is using 4-momentum, $p_\mu=(\frac{E}{c},\vec{p})$. Note that 4-momentum is conserved and $p^\mu p_\mu=-m^2 c^2$ is invariant.

Last edited: May 12, 2009