Q. A disc of mass rotates freely about a fixed horizontal axis through its centre. A thin cotton pad is fixed to its rim, which can absorb water. The mass of water dripping onto the pad is per second. After what time will the angular velocity of the disc get reduced to half of its initial value ?

System of Particles and Rotational Motion Report Error

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Solution:

Mass of cotton pad after time is

By conservation of angular momentum,

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