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A horizontal platform is rotating with uniform angular velocity around the vertical axis passing through its centre. At some instant of time a viscous fluid of mass is dropped at the centre and is allowed to spread out and finally fall. The angular velocity during this period:

  1. A
    decreases continuously
  2. B
    decreases initially and increases again
  3. C
    remains unaltered
  4. D
    increases continuously

Solution & Step-by-step Explanation

Angular momentum is conserved.As the fluid spreads from the centre to the edge, the moment of inertia increases, so decreases. When the fluid falls off, decreases back to its original value, so increases.

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A horizontal platform is rotating with uniform angular velocity around the vertical axis passing through its centre. At some instant of time a viscous fluid of mass is dropped at the centre and is allowed to spread out and finally fall. The angular velocity during this period:
A
decreases continuously
B
decreases initially and increases again
C
remains unaltered
D
increases continuously

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