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A body A of mass M is descending vertically under gravity and splits into two fragments: B of mass M/3 and C of mass 2M/3. Relative to the centre of mass of the original body A, the centre of mass of the two fragments together moves toward

1. no shift occurs
2. it depends on the height at which the body breaks
3. fragment B
4. fragment C

Correct answer: no shift occurs

Solution

Splitting is due to internal forces; the only external force is gravity, which acts identically on the combined fragments. The centre of mass of B and C continues along the original trajectory of A, so there is no shift relative to it.

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