A disk has a radius of 30 cm and a mass of 0.3 kg and is turning at 3.0 rev/s. A trickle of sand falls onto the disk at a distance of 20 cm from the center and build a 20cm radius ring of sand on it. How much sand must fall on the disk to decrease the speed to 2.0 rev/s? Idisk = 1 2mR2 ; Iring = mR

The mass of the sand that will fall on the disk to decrease the is 0.3375 kg

Explanation:

Moment before = Moment after

where;

I is moment of inertia = Mr² = 0.3 x (0.3)² = 0.027 kg.m²

substitute this in the above equation;

Therefore, the mass of the sand that will fall on the disk to decrease the is 0.3375 kg

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explanation: