Body A of mass 4m moving with speed u collides with another body B of mass 2m at rest. The collision is head-on and elastic in nature. After the collision, the fraction of energy lost by the colliding body A is:

1. $\frac{5}{9}$

2. $\frac{1}{9}$

3. $\frac{8}{9}$

4. $\frac{4}{9}$

A particle of mass 4M kg at rest splits into two particles of mass M and 3M. The ratio of the kinetic energies of mass M and 3M would be:
1.  3 : 1
2.  1 : 4
3.  1 : 1
4.  1 : 3