# Other symbols for rotational inertia?

• B
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.>

## Answers and Replies

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).

berkeman
Mentor
The symbol for electrical current is I.
Much more common is i(t) with the lower case "i". Problem solved?

Much more common is i(t)
Really? Huh, this is the first time I've encountered this.

berkeman
berkeman
Mentor
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.