What are the units for inertia?

In summary: The unit for mass is kg.Moment of inertia is the resistance to angular acceleration by torque applied to the body.
  • #1
miniradman
196
0
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... that's why I'm here :smile:

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
 
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  • #2
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.
 
Last edited:
  • #3
Or as they say: "Mass is a measure of inertia"
 
  • #4
rollcast said:
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.

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.
 
  • #5
Fewmet said:
Miniradman: I find it surprising your professors find the point debatable. I think rollcast's answer is pretty unambiguous.
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)?
 
  • #6
Hear hear.
 
  • #7
inertia is unambiguous

D H said:
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)?

First there are two terms: Inertia vs. Moment of Inertia
Second, they have different units: kg vs. kg*m2 as rollcast posted.
Third, they are different from mass or anything else:
Inertia - The tendency of a body to resist acceleration; the tendency of a body at rest to remain at rest or of a body in straight line motion to stay in motion in a straight line unless acted on by an outside force
Mass - a collection of incoherent particles, parts, or objects regarded as forming one body
Fourth, they are not mass or momentum, it has its own property. Even though the Inertia has the same unit as mass, the concept is different. The Moment of Inertia does not even have the same unit as momentum.
 
  • #8
The units for inertia are kg m^2/s^2.
 

1. What is inertia?

Inertia is the tendency of an object to resist changes in its state of motion.

2. What are the units for inertia?

The units for inertia depend on the system of units being used. In the International System of Units (SI), the unit for inertia is kilogram (kg).

3. How is inertia related to mass?

Inertia is directly proportional to mass. This means that an object with a greater mass will have a greater tendency to resist changes in its state of motion.

4. Can inertia be measured?

Inertia can be indirectly measured by observing the effects of a force on an object. The greater the force required to change an object's state of motion, the greater its inertia.

5. How does inertia affect objects in motion?

Inertia causes objects in motion to continue moving in a straight line at a constant speed unless acted upon by an external force. It also causes objects at rest to remain at rest unless acted upon by an external force.

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