What is the Moment of Inertia of a Book Pivoting at One Corner?

In summary, the problem involves finding the period of a book swinging along a plane parallel to itself, with dimensions 24 by 27 cm, pivoted at one corner. To do so, the moment of inertia is needed and can be calculated using an integral or using tables and the parallel axis theorem. The problem reduces to a simple pendulum if the book is considered a point mass at its centre of mass. If the book is hanging vertically, the concept of periodic motion is not clear.
  • #1
armolinasf
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Homework Statement



Suppose I have a book with dimensions 24 by 27 cm and its being pivoted at one of its corners so that it can swing along a plane parallel to itself. I'm supposed to find the period. But in order to do that I need to know its moment of inertia, would I have to write an integral using the definition of moment of inertia or is there some formula that I'm missing? Thanks
 
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  • #2
armolinasf said:

Homework Statement



Suppose I have a book with dimensions 24 by 27 cm and its being pivoted at one of its corners so that it can swing along a plane parallel to itself. I'm supposed to find the period. But in order to do that I need to know its moment of inertia, would I have to write an integral using the definition of moment of inertia or is there some formula that I'm missing? Thanks

If you consider the book to be a point mass, at the centre of mass of the book, the problem will reduce to a simple pendulum.
 
  • #3
The...period? Do you mean that the book is hanging vertically and acting as a physical pendulum? Because if it's horizontal, it's not even clear to me that you'd have a periodic motion.

You could integrate to find the moment of inertia, but moment of inertia tables will certainly have equations for the moment of inertia of a thing rectangular slab, and you could use the parallel axis theorem to get this for rotation around one of its corners ("thin" here meaning that you can ignore the third dimension -- the thickness).

See for example, here: http://en.wikipedia.org/wiki/List_of_moments_of_inertia
 

1. What is the moment of inertia of a book?

The moment of inertia of a book is a measure of how difficult it is to change the book's rotational motion. It is also known as the angular mass or rotational inertia.

2. How is the moment of inertia of a book calculated?

The moment of inertia of a book can be calculated using the formula I = mr², where I is the moment of inertia, m is the mass of the book, and r is the distance from the axis of rotation to the book's center of mass.

3. What factors affect the moment of inertia of a book?

The moment of inertia of a book is affected by its mass, shape, and distribution of mass. A book with a larger mass or a wider distribution of mass will have a higher moment of inertia, while a book with a smaller mass or a more compact distribution of mass will have a lower moment of inertia.

4. How does the moment of inertia of a book affect its rotational motion?

The moment of inertia of a book determines how quickly it will rotate and how much force is required to change its rotational motion. A book with a higher moment of inertia will rotate more slowly and require more force to change its rotational motion, while a book with a lower moment of inertia will rotate more quickly and require less force to change its rotational motion.

5. Can the moment of inertia of a book be changed?

Yes, the moment of inertia of a book can be changed by altering its mass, shape, or distribution of mass. For example, adding or removing pages from a book will change its mass and therefore its moment of inertia. Similarly, changing the book's shape or how its mass is distributed will also affect its moment of inertia.

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