Conservation of Angular Momentum

AI Thread Summary
The discussion focuses on a physics problem involving two disks with different moments of inertia and angular speeds that are brought together on a common shaft. The key concept is the conservation of angular momentum, which states that the total angular momentum before the disks are combined must equal the total angular momentum after they are combined. Participants emphasize the need to calculate the initial and final kinetic energies to determine the final kinetic energy as a fraction of the initial kinetic energy, which is given as 49/52. The conversation highlights the importance of applying the equations for angular momentum and rotational energy to solve the problem effectively. Understanding these principles is crucial for grasping the concept of angular momentum conservation in rotational dynamics.
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Homework Statement


Two disks with moments of inertia I and 31 are mounted on a common shaft with frictionless bearings. They are initially rotating with angular speeds of w and 2w. They are brought together without being disturbed. What is their final KE as a fraction of their initial KE?

The answer is 49/52 but i don't understand the concept of it.
can someone please explain?

Equations:
Angular Momentum: Iw = Iw
 
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You will need to use conservation of angular momentum and conservation of rotational energy.

Start by writing out these quantities for each disk and then when the disks are brought together.
 

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