Hypothetical question on Inertia

[easttiger2007]

If we could imagine an object in space which does not obey the law of inertia ( ie it offers no resistance to motion) how would it react to a force applied to it? Since it offers no resistance to a force the concept of acceleration would no longer apply (There would be no rate of change of motion). Does this mean it would instantaneously attain a certain velocity and what would that velocity be?

The discussion goes too far. The question is simple, but need to be clarified by classifying into following two cases.
Case 1. Just the NSL changes its form, say f=m^2*a or or f=sin(m)*a etc. This will be a problem of mathematical deduction.
Case 2. Inertia just vanish completely. Then it can be regard as a limit of some real situation. For example, a light bead on a horizontal frame which can response to any significant horizontal force with nearly infinite acceleration.

 

[TVP45]

Sim Wa.
The OP insisted on a hypothetical object with at least one of it's commonly understood properties suppressed. An object is commonly understood to be anything capable of being perceived by our senses. A hypothetical object is thus anything which we can imagine being perceived by our senses. I have seen the edge of a shadow. QED.
If one asks a question about a hypotetical object, then one should expect an answer containing a hypothetical object. In fact, I suspect there is great similarity between a shadow and the hypothetical object posited, i.e, how does an object not subject to a field interact with a field?
Bohr had a great line which may apply here:
It is wrong to think that the task of physics is to find out how Nature is. Physics concerns what we say about Nature.
Tom

 

[vanesch]

If I may add something to this sometimes hallucinating thread
The OP asked essentially what happens if an object's inertial mass is zero, and if we exert a force on it. But the problem is: what does it mean to "excert a force" on an object ? Usually, this results from an interaction with a given prescription of how the momentum of the object changes, but this object doesn't have any !
Does the object have a position in space at a given instant, or is it position-less too ?
So you cannot ask what would happen if we exert a force on it, because that would mean that we should give a law saying how its momentum is changing, while it hasn't gotten any. In other words, it is meaningless to talk about exerting a force to an object for which momentum doesn't have a meaning, as force is change in momentum.
You could just as well ask what would happen to a position-less object when we apply an acceleration to it. Force is change in momentum. If there's no momentum, it cannot change it.

 

[novaa77]

So you cannot ask what would happen if we exert a force on it, because that would mean that we should give a law saying how its momentum is changing, while it hasn't gotten any. In other words, it is meaningless to talk about exerting a force to an object for which momentum doesn't have a meaning, as force is change in momentum.
You could just as well ask what would happen to a position-less object when we apply an acceleration to it. Force is change in momentum. If there's no momentum, it cannot change it.

All matter (physical substance as defined by the Oxford dictionary) is capable of acceleration. The question is, is inertia an inherent property of matter, or is it a result of external influences that cause inertia and thus give us the "effect" of mass.

 

[tabchouri]

i would say the first hypothesis. inertia is inherent to mass.-----------------------------------------------------
Correct me if I am wrong.
http://ghazi.bousselmi.googlepages.com/présentation2

 

[pallidin]

Without mass, the inertial phenomenon does not express it's potential. Without the movement of mass, the inertial quality similarly does not express the event.
As mass bends space-time, it is not inconceivable that inertia is a consequence of this asymmetric "drag"

 

[loom91]

There is almost no physics in this entire discussion. It's some semantic debates and some veiled name calling.

The OP's question is what would happen if a particle had mass but not inertia. Mass can mean either inertial mass or gravitational mass. Inertial mass and inertia are equivalent, so it's not meaningful to say one is present while the other is not.

Mass may also mean gravitational mass. Since zero inertial but nonzero gravitational mass violates the equivalence principle, and no known physical phenomena violates the equivalence principle, such a hypothetical particle may spontaneously metamorphose into a bowl of petunias for all we know.

Molu

 

[Doc Al]

I think that's an excellent note on which to close this thread, which has outlived any usefullness it may have had.