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NTA Abhyas JEE Main2020PhysicsCenter of Mass, Momentum and CollisionPractice

A 12 kg bomb at rest explodes into two pieces of 4 kg and 8 kg . If the momentum of 4 kg piece is 20 Ns , the kinetic energy of the 8 kg piece is

Options

  1. A25   J
  2. B20   J
  3. C50   J
  4. D40   J

Correct answer

A. 25   J

Step-by-step solution

The explosion is due to internal forces so the momentum of the system is conserved. Applying conservation of momentum, 0 = m 1 v + m 2 v ′  0 = 20 + 8 v ′ v ′ = - 20 8 = - 5 2   m   s - 1 After the explosion, Then, K E = 1 2 m v ′ 2 = 1 2 × 8 × 5 2 2 = 1 2 × 8 × 25 4 = 25   J

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