Other symbols for rotational inertia?

In summary, there are multiple symbols that can be used for rotational inertia, such as I, J, or ##\Theta##, but the more common symbol for electrical current is i(t), with the lower case "i". Both symbols can be used interchangeably, but it is important to explain and clarify which symbol is being used in your work.
  • #1
yrjosmiel
53
5
So I'm currently doing a project on motors. It just so happens that I'm dealing with both electrical current and rotational inertia. I have one small problem.

The symbol for electrical current is I. But so is rotational inertia! Are there any other symbols for rotational inertia/electrical current?

<Moderator's note: Questionable use of language removed.>
 
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  • #2
yrjosmiel said:
Are there any other symbols for rotational inertia/electrical current?

I have seen I, J or ##\Theta## as symbols for moment of inertia but you can use any symbol you want if you explain it suffitiently (e.g. with a corresponding comment at the first use).
 
  • #3
yrjosmiel said:
The symbol for electrical current is I.
Much more common is i(t) with the lower case "i". Problem solved? :smile:
 
  • #4
berkeman said:
Much more common is i(t)
Really? Huh, this is the first time I've encountered this.
 
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  • #5
yrjosmiel said:
Really? Huh, this is the first time I've encountered this.
Well, in fairness, it's commonly written both ways, but maybe more often as "I" for DC and more often as "i(t)" for AC and time-varying currents. In any case, you certainly can choose to use either, and since your work involves I=MOI, you can chose to use i(t) for your current in your equations. :smile:
 

1. What is rotational inertia?

Rotational inertia, also known as moment of inertia, is a measure of an object's resistance to changes in its rotational motion. It depends on the object's mass, shape, and distribution of mass around its axis of rotation.

2. How is rotational inertia different from linear inertia?

Rotational inertia is similar to linear inertia, which is an object's resistance to changes in its linear motion. However, rotational inertia specifically refers to an object's resistance to changes in its rotational motion, while linear inertia refers to an object's resistance to changes in its linear motion.

3. What are some common symbols used to represent rotational inertia?

The most common symbol used to represent rotational inertia is I. Other symbols that may be used include J or MR2, where M is the mass of the object and R is the distance between the object's axis of rotation and its mass distribution.

4. How does the shape of an object affect its rotational inertia?

The shape of an object can greatly affect its rotational inertia. Objects with a larger moment of inertia will have a greater resistance to changes in their rotational motion. For example, a solid sphere has a larger rotational inertia than a hollow sphere with the same mass and radius.

5. How is rotational inertia calculated?

Rotational inertia can be calculated using the equation I = MR2, where I is the moment of inertia, M is the mass of the object, and R is the distance between the object's axis of rotation and its mass distribution. For more complex shapes, the rotational inertia can be calculated using integrals or using tables of moments of inertia for common shapes.

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