# Does the inertia of an object ever change?

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1. Feb 2, 2016

### Balsam

If the mass of an object is the same, does the inertia ever change. For example, is the inertia of a person different if they are on the surface of the earth than if they are orbiting earth or in outer space?

2. Feb 2, 2016

### Staff: Mentor

This question would probably be best served by a discussion of inertia in the General Physics forum. I'll move it there.

3. Feb 2, 2016

### CWatters

Perhaps have a look at the difference between inertia (in a straight line) and the moment of inertia (rotation).

4. Feb 2, 2016

### Aniruddha@94

I'm not too sure about this, but I don't think it does.. Regardless of where the body is or what type of force is acting on it, its motion is dictated by F(net)=ma
So it looks like inertia is an innate property of the body

5. Feb 2, 2016

### Nick tringali

No, Inertia does not change, it is mass related and it is the resistance to change of motion

6. Feb 3, 2016

### CWatters

That's true for linear inertia. For rotation the moment of inertia depends on the distribution of the mass as well as the amount of mass.

T = Iα

where T is Torque, I is the moment of Inertia and α is the angular acceleration

7. Feb 3, 2016

### Khashishi

Inertia is a term used for an abstract concept or law, not an extrinsic quantity for a system. If you want a quantity, it's better to say inertial mass, which is probably what you mean by your context. Of course, inertial mass is just the same thing as mass, so your original question is trivial. It is possible that there are two kinds of mass, inertial mass and gravitational mass, but general relativity tells us that these are the same thing.