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NEET Sample Paper NEET Sample Test Paper-72

  • question_answer
    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 m 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

    Correct Answer: B

    Solution :

    From law of conservation of angular momentum, if no external torque is acting upon a body rotating about an axis, then the angular momentum of the body remains constant, that is, \[J=I\omega =constant\] Hence, if I decreases, co increases and vice-versa. When liquid is dropped, mass increases hence increases\[(I=m{{r}^{2}})\]. So, decreases, but as soon as the liquid starts falling \[\omega \] increases again.


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