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Let's talk about this question.
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We are given that two disks are rotating about the same axis.
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This is a moment of inertia of 3 kilogram meter square and has an angular velocity of 7 .97 radium per second.
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So let's call this this is the initial stage.
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And we have a disk a, which is rotating about this axis.
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And there is another disk b which is rotating about the same axis.
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Axis, but the same axis with another angular velocity.
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So if you notice the angular velocity of this one is opposite to the previous one.
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After that, the two disks stick together and they both start rotating as a single unit with another angular velocity.
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Let's call this omega 1, let's call this omega 2, and let's call this omega 3.
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Worth noticing is this is without the aid of any external torque.
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So the axis of rotation for this unit is also the same as that of the separated disks.
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So we need to find the moment of inertia of the disk b.
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So this is based on the concept of the conservation of angular momentum.
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So we are going to say conservation, conservation of angular momentum.
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Why the angular momentum is conserved because there is no external torque associated with it.
01:31
So we're going to say we're going to write that initial angular momentum of a plus initial angular momentum of b that's going to be same as the angular momentum of a plus b afterwards...