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NEET2012PhysicsCenter of Mass, Momentum and CollisionActual

A body of mass m₁=4 ~kg moves at 5 i~ m / s and another body of mass m₂=2 ~kg moves at 10 i~ m / s . The kinetic energy of centre of mass is

Options

  1. A200 3 ~J
  2. B500 3 ~J
  3. C400 3 ~J
  4. D800 3 ~J

Correct answer

C. 400 3 ~J

Step-by-step solution

v_ CM = m₁ d r₁ d t +m₂ d r₂ d t m₁+m₂ = 4 5 i +2 10 i 4+2 v_ CM = 40 i 6 = 20 3 i The kinetic energy K= 1 2 m v^2= 1 2 (4+2) 20 20 3 3 = 1 2 6 20 20 3 3 K= 400 3 ~J

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