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 :

8/9

\(\frac{\Delta K}{K} = 4\frac{m_1m_2}{(m_1 + m_2)^2}\)

\(m_1 = 4m ; m_2 = 2m\)

\(\frac{\Delta K}{K}\) = \(\frac{8}{9}\)