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NEET2015PhysicsCenter of Mass, Momentum and CollisionActual

Two spherical bodies of mass M and 5M and radii R and 2R released in free space with initial separation between their centres equal to 12R. If they attract each other due to gravitational force only, then the distance covered by the smaller body before collision is:

Options

  1. A2.5R
  2. B4.5R
  3. C7.5R
  4. D1.5R

Correct answer

C. 7.5R

Step-by-step solution

Initial position, For collision, both bodies have to travel distance = 12 R - 3 R = 9 R Since the bodies move under the mutual forces, centre of mass will remains stationary, m 1 x 1 = m 2 x 2 M x = 5 M ( 9 R - x ) x = 45 R - 5 x 6 x = 45 R x = 45 R R = 7.5 R

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