Inertia

[Silvertiger]

I have been fascinated by this property unique to matter for a very long time, and have never been satisfied with its meaning in physics. Note: this is my own work and findings.

"Inertia is the tendency of a mass to resist any change in motion." That is the standard definition, and I agree with it. But the devil is in the details.

Just a little information to get us all on the same page:
Mass is not only the stuff of matter, but it is also a measure of inertia. So we use mass itself to define a thing's resistance to a change in motion (or position.) Therefore, aside from the simple expression I=m, couldn't we just also mathematically express it as I=Δmv? We shall see. But do not confuse this with impulse, as impulse is derived in a different way and therefore has a different meaning in the language of physics, like how a word in the English language can have more than one meaning depending on how it is used. Impulse [J] is a measure of a force applied for a duration of time.

How impulse is derived: From N2, we have F=ma. We then break it down into F=m(Δv/Δt). We rewrite it as FΔt=mΔv. We already know that impluse is a force with a duration, so we can replace FΔt with J to get J=mΔv

But physics does not write the expression as I=Δmv (or I=Δρ) because it assumes that an object at rest has inertia...when in point of fact it doesn't! Physics says that inertia is NOT a force...when in point of fact it is! As for me, I do not use this equation either because it only describes a change in motion...not an object's resistance to that change.

Here's why: Inertia is a resistance to a change in motion. This means that it falls under the purview of N3, as well as N1. N1 should be a subset of N3. N3 states that for every action there is an equal and opposite reaction. Well gentlemen, inertia is HALF of that, as it is 100% reactive, meaning that it is a reactive force generated by a net force that acts to move a mass. N3 is mathematically expressed as Fa=-Fr, where a is the acting force and r is the reactive force. Inertia is sitting on the right side of that equation! Therefore, I≠m!

So now, we can accurately express inertia as I=-Fr. And so here we are:

I≠m
I=-Fr
I=-(ma)r

Inertial Potential:
If inertia is a reactive force against a net force that acts to change an object's current state of motion, then an object without a net force that acts has an inertial potential that is stored, measured by mass: IP=m This expression states that it has the potential to resist a change in motion as long as it has mass. (I write this expression solely to differentiate it from inertia. If you notice, this is the original expression, now set apart from inertia and defined.)

Kinetic Inertia:
This is the exact same thing as momentum: KI=mv
KI=IPv; m=KI/v; v=KI/IP; v=KI/m


Conclusions:

1. Inertia is an object's resistance to a change in its current state of motion.
2. Inertia is the reactive force against the net force that acts to change an object's current state of motion.
__2.a. Mass cannot be the measure of inertia based on this.
__2.b. An object at rest has an inertia of zero.
3. An object without a net force acting has no inertia, but an inertial potential.
4. Mass is a measure of inertial potential.


Love to read some thoughts on this. Does any of this make sense? :)

[eccentrically1]

I≠m
I=-Fr
I=-(ma)r

Negative mass doesn't make sense.

[agor95]

I have read your view on this subject.

It is good to look at the world from another direction.

When I did that I started with one electron in a void.

Then equated inertia to the back electromagnetic field.

Regards

[Silvertiger]

I≠m
I=-Fr
I=-(ma)r

Negative mass doesn't make sense.

It isn't. The mass is negatively accelerated against the force that is being applied, so the whole term becomes negative thru multiplication. The negative is the direction, as force is a vector and not a scalar quantity. :)

[Silvertiger]

I have read your view on this subject.

It is good to look at the world from another direction.

When I did that I started with one electron in a void.

Then equated inertia to the back electromagnetic field.

Regards

Thanks agor. The other way I look at it is as a function of time. It's a little more difficult and so I am still working on it. I myself cannot look at it as a result of a back EMF reaction as not all mass produces them, and would imo have a subset only for those types of masses that would be added to any additional force and would be inclusive of the sum of forces.

Thanks for sharing. :)

[Art]

Some initial "reactive thoughts"

:--

+++

"So we use mass itself to define a thing's resistance to a change in motion (or position.)"

So to measure the Inertia we measure the masses resistance to a force applied.

The "inertia " is considered to be a property of the matter . No matter , no Inertia .

The force of I (reaction force) is presumably in a linear relationship to the mass . Double the mass , double the force etc.

Mass we define as matter and we measure the quantity (in practice) by weighing it .

Therefore our measurement of mass depends on the force of gravity and gravitational force is therefore implicated in all discussions about Inertia
at our current state of knowledge.

ie we can't ignore it until we can somehow factor it out of the discussion .

Also we have to include it until we know (experimentally I think) that the inertial measurements
of a set mass in a strong gravitational field is the same as in a weak one .

( I wonder if NASA or anyone has ever performed experiments along these lines ? )

+++

Quote " because it assumes that an object at rest has inertia...when in point of fact it doesn't! Physics says that inertia is NOT a force...when in point of fact it is! As for me, I do not use this equation either because it only describes a change in motion...not an object's resistance to that change. "

---

Good point . Because physics says it is a property , we tend to ignore it under the different conditions that matter might find itself in .

We don't know if Inertia is a property that relies on the position and motion of matter in relation to the "average" gravitational force of all the matter in the Universe (its centre of mass) or the mass's relationship to its sub atomic components etc .

That matters I think because to measure it we need to have a reference system to measure the force against .
Does that make sense ?

Currently we can't measure it unless we exactly match its speed of movement etc ?

+++

Quote "2.a. "Mass cannot be the measure of inertia"

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Yes , definitely agree

++++

Quote 2.b. "An object at rest has an inertia of zero. "

---

Dunno ! I think its possible to think of "gravitational attraction " as a type of "Vectored Inertia" if you have a few stiff drinks and practice looking inwards like a Dervish .

++++

Quote "The other way I look at it is as a function of time."

---

Agree , because forces are involved you need to .

+++

MOMENTUM .---- I think you have to do a bit of thinking in this area for sure . Inertia basically defines momentum IMO.

+++

Good going ! , this is an overdue thread ! - well done ST : )

[ME]

Some annoying questions:

1. Inertia is an object's resistance to a change in its current state of motion.
The question remains: why?

2. Inertia is the reactive force against the net force that acts to change an object's current state of motion.
Like friction?

__2.a. Mass cannot be the measure of inertia based on this.
Why not?

__2.b. An object at rest has an inertia of zero.
So Inertia is variable?
Isn't "being at rest" actually a clear sign of maximum Inertia?

3. An object without a net force acting has no inertia, but an inertial potential.
Isn't that momentum? (when comparing two objects)

4. Mass is a measure of inertial potential.
Isn't this circular?

...
Why off-topic?

[John Collins]

Yes an object at rest does have maximum inertia. Try pushing a car that wont start!

JC

[Silvertiger]

Some annoying questions:

1. Inertia is an object's resistance to a change in its current state of motion.
The question remains: why?

2. Inertia is the reactive force against the net force that acts to change an object's current state of motion.
Like friction?

__2.a. Mass cannot be the measure of inertia based on this.
Why not?

__2.b. An object at rest has an inertia of zero.
So Inertia is variable?
Isn't "being at rest" actually a clear sign of maximum Inertia?

3. An object without a net force acting has no inertia, but an inertial potential.
Isn't that momentum? (when comparing two objects)

4. Mass is a measure of inertial potential.
Isn't this circular?

...
Why off-topic?

This is great. Thanks for these good questions ME. :)

1. Because all tasks take time to accomplish, and jnertia ks a function of time.

2. Not quite. Although friction is a reactive force, it does not arise as a property of mass itself, but it is a nonconservative dissipative force that occurs when the surface areas of two masses interact in different directions.

2.a. Because mass is a thing; not a force.

2.b. Yes to the first question as it is a dependent variable of the force applied. No to the second question because inertia is a resistance to a change in motion. Ergo, if there is nothing to resist then the resistance does not exist...but it had the potential to resist based on the quantity of mass to be moved, which is why I differentiated this definition as "inertial potential."

3. No. Inertial potential is the ability to resist a change in motion based on the quantity of mass. Kinetic inertia, an active resistance to an applied force, is momentum...or rather the change in momentum, similar to impulse, but based as the reactive force -Fr while in motion. Thank you for this question, as I need to update that definition now. An object with momentum (in motion) also has no inertia, but if it has a CHANGE in momentum, then it does, and that resistance will occur throughout the duration of that change! :D

Edit for Kinetic Inertia:
KI=-Fr (this is just simply inertia; it doesn't have to be called "kinetic" since that is a given.)

4. No, as I separated inertia into inertial potential and inertia.

Definitions Update:
Inertia: I=-Fr
Inertial Potential: IP=m
Inertia is proportional to delta mv and therefore proportional to impulse: I~△mv; I~J

[ME]

1. Inertia is an object's resistance to a change in its current state of motion
The question remains: why?
1. Because all tasks take time to accomplish, and inertia is a function of time

I don't get it. What you have in mind may apply to some situations, but I don't think to the broader sense of inertia.

Velocity takes time, and a change in velocity (acceleration) takes time too. But Inertia just 'resists' a new velocity.
With either springs or sticks it is possible to transfer the same amount of force to an object so it eventually goes at a certain velocity. I think 'Time' in this particular instance is only a factor for eventually observing that end-velocity which, in this case, does not resist that new velocity at all. On the other hand, Mass does remain a discriminator for the final velocity.

__2.a. Mass cannot be the measure of inertia based on this.
Why not?
2.a. Because mass is a thing; not a force.

When you state that Inertia is a force, and mass a thing, then your statement is correct.

I think mass is an effect; perhaps just like tension. And, I think, inertia is an effect of mass. Before we start to yes/no-around then perhaps I need to add a few of my own words*

__2.b. An object at rest has an inertia of zero.
So Inertia is variable?
Isn't "being at rest" actually a clear sign of maximum Inertia?
2.b. Yes to the first question as it is a dependent variable of the force applied. No to the second question because inertia is a resistance to a change in motion. Ergo, if there is nothing to resist then the resistance does not exist...but it had the potential to resist based on the quantity of mass to be moved, which is why I differentiated this definition as "inertial potential."

This still sounds a lot like the behavior of friction to me.
In principle I think there's no argument against your "ergo". But I suspect a cause/effect anomaly is a possible factor.
When I don't put my fingers into the fire, they won't burn; but does that mean the fire actually doesn't burn when I'm not near?

Anyway, how would we graph this behavior?
But more importantly: do your tweaks predict inertial behavior better?

4. Mass is a measure of inertial potential. Isn't this circular? 4. No, as I separated inertia into inertial potential and inertia.

Sounds complicated.
Does this mean we could in theory pump more inertia into (or drain) an object while the mass remains constant?

*I probably need a few words, but I think I have a simpler way of viewing inertia.

[Silvertiger]

I don't get it. What you have in mind may apply to some situations, but I don't think to the broader sense of inertia. Velocity takes time, and a change in velocity (acceleration) takes time too. But Inertia just 'resists' a new velocity.

Without time, inertia would not exist, as all accelerations would be instantaneous, and therefore not resisted.

When you state that Inertia is a force, and mass a thing, then your statement is correct.

I did state that inertia is a force, rendered as I=-Fr, which is reacting equal and opposite to a force, Fa, that acts against a mass.

This still sounds a lot like the behavior of friction to me. In principle I think there's no argument against your "ergo". But I suspect a cause/effect anomaly is a possible factor.

It sounds like friction because both inertia and friction are drag forces. However, the difference between the two is that friction is one mass dragging the motion of another mass along the contacted surface areas, while inertia is a drag against spacetime. A simple visual is to imagine how a submarine moves against water. (This is how warp theory works, in that space is treated as a "special" type of fluid, known as a "superfluid," a fluid of zero viscosity that can be displaced (compressed and rarefacted) by a mass that occupies it. Warp theory basically says that if you curve the space ahead of and behind a mass in line with its motion vector, then inertia is rendered moot. Gravity at this point is just a compression gradient.) And yes, the entire relationship is causal.

Anyway, how would we graph this behavior?

X-axis: time
Y-axis: inertia

But more importantly: do your tweaks predict inertial behavior better?

All we can do is try it out. :)

[unstable]

ST wrote "Without time, inertia would not exist, as all accelerations would be instantaneous, and therefore not resisted"

Without time even acceleration would not exist. It is not possible to imagine how things would behave without time.

Yes an object at rest does have maximum inertia. Try pushing a car that wont start!

JC

Ok it's a joke but ... no... try to stop a car in motion. :-)

ST, Interesting thread ... I read carefully.

[unstable]

It will seem obvious but it is what appears: (kinetics) energy exchange between masses. At the highest level, it is not possible to understand whether the initial condition is quiet or motion, because the reference is missing (I mean: referring to what ? which mass ? to all the expanding universe ?). Only one state relative to another subject is noted.

So I would say that inertia is the result of an exchange of energy between matter. The behavior of the masses in space is quite logical. What forces a mass to move or stop can only be "energy" supplied by another mass and to the detriment of its energy. Be it by impact (collision), gravitational, magnetic or other interaction that causes spatial movement transfer.
depending on the transfer method of kinetic energy, the amount of energy transferred between two masses is influenced by time.
More than the properties of matter, I would say that it is the property of the global field of forces in which matter is present. Let's call it space-time or how we prefer to call it. The universal forces that pervade every point of the universe itself. We will never understand it in detail. It would be like understanding the meaning of organic life and self-consciousness ... I suppose. It is something beyond our capacity of observation and understanding.
The content can not understand the container :-)

(All I have written is obviously ONLY my point of view on this matter.)

[Art]

ST

Quote " Warp theory basically says that if you curve the space ahead of and behind a mass in line with its motion vector, then inertia is rendered moot."

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Is there any evidence stated that you know of that might take this part of that theory out of the realm of speculation ?


I'm of the opinion that the curving space time theory is really a nice mathematical way of explaining why light curves in a gravitational field . However It really is only a mathematical shortcut to "explain" something that current theorists would rather not admit to , ie that light has "mass" and is affected by gravity .

I don't think the evidence they site (ie that starlight is bent by just the right amount as it passes the Sun ) as sufficient to prove curved spacetime .


If there is some evidence which backs up the warp theory without relying on any circular thinking about curved space time then " I'm In " but not otherwise .

[ME]

Light does not suddenly have mass.
Mass just causes space/time to curve; it actually makes gravitational acceleration fictitious.

Still needs to be checked though...
http://sci.esa.int/hubble/60441-hubble- ... -heic1812/

Or,

The orbit of S2 will give astronomers an opportunity to test for various effects predicted by general relativity and even extra-dimensional effects.[10] These effects reached a maximum at closest approach, which occurred in mid-2018.[11][12] Given a recent estimate of 4.31 million M☉ for the mass of the Sagittarius A* black hole and S2's close approach, this makes S2 the fastest known ballistic orbit, reaching speeds exceeding 5,000 km/s (11,000,000 mph, or 1/60 the speed of light) and acceleration of about 1.5 m/s2 (almost one-sixth of Earth's surface gravity)
https://en.wikipedia.org/wiki/S2_(star)

Observation: https://youtu.be/wstMu4ZndM8


But when we need complex speculative warp-technology to explain something as fundamental as Inertia then things go haywire very quick. I need to say, it happens often on this forum; perhaps I get used to it someday.