Special relativity collisions problem

[deadringer]

Homework Statement

We have two particles mass m called p1 and p2. P1 is stationary, p2 has energy E. They annihilate to produce to particles of mass 100m. We need to find the min value of E

Homework Equations

The Attempt at a Solution

I suspect that the minimum initial energy of collision in the LAB frame is such that the CM frame energy is just enough to create the particles i.e that they are stat afterwards. In which case they would coalesce in the LAB frame (or any other). Is this true?

 

[Dick]

Right. You need 100m in the CM frame (where total momentum=0).