# Moment of inertia

1. Mar 1, 2005

### Tabe

does anyone know an easier way to determine which formula is used for calculating moment of inertia? i have all the formulas and descriptions, but i have trouble figuring out which formula to use based on what is given in the problem. any ideas thatll help me?

2. Mar 1, 2005

### dextercioby

If you have all the formulas,what are you asking for...?The expression for the tensor of inertia...?The definition of axial moment of inertia:
$$I_{O}=:\int r^{2} \ dm$$

,or what...?

Daniel.

3. Mar 1, 2005

### HallsofIvy

Staff Emeritus
What formulas do you mean?

4. Mar 1, 2005

### Tabe

I mainly need to know how to determine the axis, and the difference between a hoop and a cylinder...mainly, (MR^2) and (1/2 MR^2)

5. Mar 1, 2005

### dextercioby

You're usually told which axis you rotate the object about.And yes,there are 2 more things:the theorem of Steiner and the integral calculus...
Are u familiar with them ?

Daniel.