NEET2019PhysicsCenter of Mass, Momentum and CollisionActual
Body A of mass 4 m moving with speed u collides with another body B of mass 2 m 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
Options
- A1 9
- B8 9
- C4 9
- D5 9
Correct answer
B. 8 9
Step-by-step solution
4 m u + 0 = 4 m v 1 + 2 m v 2 ⇒ 2 u = 2 v 1 + v 2   … ( A ) For elastic collision, e = 1 ⇒ u = v 2 - v 1   … ( B ) From A   and B , 4 u = 3 v 2 ⇒ v 2 = 4 3 u and v 1 = u 3 Fraction of energy lost by ( A ) , = 1 2 4 m u 2   -   1 2 4 m v 1 2 1 2 4 m u 2 = u 2   -   u 2 9 u 2 = 8 9