Question
Question: A horizontal platfrom is rotating with uniform angular velocity around the vertical axis passing thr...
A horizontal platfrom is rotating with uniform angular velocity around the vertical axis passing through its centre. At some instant of time a viscous fluid of mass 'm' is droped 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
Answer
Decreases initially and increases again
Explanation
Solution
According to law of conservation of momentum,
Iw = constant.
When viscous fluid of mass m is dropped and start spreading out then its moment of inertia increases and angular velocity decreases. But when it falls from the platform moment of inertia decreases so angular velocity increases again