**1. The problem statement, all variables and given/known data**A particle of mass m and kinetic energy K strikes and combines with a stationary particle of mass 2m, producing a single composite particle of mass √17 m. Find the value of K

**2. Relevant equations**

E= γmc^2 , p = λmv

**3. The attempt at a solution** I have tried many times at this and have used the conservation of energy and conservation of momentum but I seem to get nowhere. The equations are definitely solvable and this seems to just be algebraic manipulation. My question is whether there is any way to simplify these problems as I just cannot get an expression for K without the other variables, this problem keeps cropping up in other questions too!

http://ift.tt/1k4l4yH