What are the units for inertia?

miniradman

Hello there, there have been a lot of conflicts between my physics teachers and university lecturers about the the units for intertia. Some say there aren't any units for inertia, and others say that it's in n/s. However, I don't know who to believe anymore... thats why I'm here

Also, if there aren't any units for inertia, why is that? Also, does "moment of inertia" differ from "inertia"? If so, how and why?

cheers - miniradman

rollcast

The unit for inertia is the same as the units for mass, kg, the unit of moment of inertia is $$ kg.m^{2}$$

Inertia is the resistance to linear acceleration by a force applied to the body.

Moment of inertia is the resistance to angular acceleration by torque applied to the body.

xAxis

Or as they say: "Mass is a measure of inertia"

Fewmet

Miniradman: I find it surprising your professors find the point debatable. I think rollcast's answer is pretty unambiguous.

If you find it easier to start with a slightly less mathematical definition, mass determines how hard it is change a body's translational motion. Moment of inertia is determines how hard it is to change a body's rotational motion.

D H

rollcast's answer may be unambiguous, but the term "inertia" is not. Does it mean mass or momentum? That's why you won't see the term used much in physics texts. Why use an ambiguous term when there are perfectly good, unambiguous alternatives (i.e., mass and momentum)?

sophiecentaur

Hear hear.