How Do You Calculate the Moment of Inertia for a Disk Rotating About Its Edge?

In summary, moment of inertia is a measure of an object's resistance to change in its rotational motion, calculated by multiplying the mass of an object by the square of its distance from the axis of rotation. For a disk, the moment of inertia can be calculated using the formula I = ½mr², where m is the mass of the disk and r is the radius. The moment of inertia varies for different shapes of disks due to differences in mass distribution. It also changes with orientation, as the distance from the axis of rotation changes. Moment of inertia is important in rotational motion as it affects acceleration, energy, and stability of an object.
  • #1
deezy
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Homework Statement


What is the moment of inertia of an 8 kg, 40 cm diameter disk for rotation through the edge of the disk?


Homework Equations


[tex]I = \frac{1}{2}MR^2[/tex]


The Attempt at a Solution



Inertia at the center of the disk would be [tex]I = \frac{1}{2}MR^2[/tex], right? I'm not sure what the right equation for inertia at a point on the edge of a disk would be.
 
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  • #2
Apply the parallel axis theorem to find the moment of inertia about a parallel axis a distance d from the centre of mass:

[tex]I = I_{cm} + Md^2[/tex]AM
 

FAQ: How Do You Calculate the Moment of Inertia for a Disk Rotating About Its Edge?

What is the definition of moment of inertia?

Moment of inertia is a measure of an object's resistance to change in its rotational motion. It is the product of the mass of an object and the square of its distance from the axis of rotation.

How is moment of inertia calculated for a disk?

The moment of inertia for a disk can be calculated using the formula I = ½mr², where I is the moment of inertia, m is the mass of the disk, and r is the radius of the disk.

How does the moment of inertia change for different shapes of disks?

The moment of inertia for a disk depends on its mass and how its mass is distributed around the axis of rotation. For different shapes of disks, the mass distribution will vary, resulting in different values for moment of inertia.

Does the moment of inertia of a disk change with its orientation?

Yes, the moment of inertia of a disk will change with its orientation. This is because the distance from the axis of rotation changes when the disk is rotated, and the moment of inertia is directly proportional to the square of this distance.

Why is moment of inertia important in rotational motion?

Moment of inertia is important in rotational motion because it affects an object's acceleration and energy in rotational motion. It also plays a role in the stability and balance of an object during rotation.

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