Inertia, a fictitious type of force?
In another thread, Eccentrically1 posted a number of points of contention.
Rather than try to address ALL of these points of contention here in one post, let us take up only one or two points at a time. First, the background…
Jim_Mich wrote:Over eight MILLION hits concerning the phrase "Inertial Force"
Eccentrically1 wrote:That's not a surprise, there are over 19 million hits for unicorns, a fictitious type of horse.
Jim_Mich wrote:Inertia most definitely produces a force. So don't give me any crap that it’s not a force. It is the negative force which must be acted against for a body to accelerate. And depending upon your frame of reference is can also be a positive force.
Let us look at the following, which are related. Let us look and discuss what these have in common and the differences between each pair.Eccentrically1 wrote:It's not crap. Inertial force on wikipedia, the online encyclopedia we all love to use, redirects to fictitious force. So inertia, or, a body’s inertial mass, produces a fictitious force, if you prefer saying it that way. A real force, like friction for instance, can exist in either an inertial frame or a non-inertial frame.
Inertial force -vs- momentum force
Fictitious force -vs- real force
I think we both agree as to what momentum is. It is the mass of an object times the velocity of the object. But the velocity of the object must be measured relative to some background inertial frame of reference. Ah, so right from the start, momentum has some relationship to inertia. So, in order to understand momentum, we need to also understand inertia.
An inertial frame of reference is normally considered to be the observer, who is considered to be stationary. Though in the big scheme of things, stationary is often considered to be the surface of the Earth, which is flinging itself thru space at some astronomical speed. But I digress. The most common inertial frame of reference is the Earth.
Inertia is often considered to be simply the mass of an object. Mass is different than weight. Gravity on our moon is a fraction of gravity on the Earth. In the Metric system of units and measurement, our gravity force is measured in kilograms of force. Inertia is also measured in kilograms. This is because inertia is the measurement of how much kilograms of force are required to accelerate one molecular equivalent of material. Each molecule of matter contain a specific number of atoms. And each atom contain a specific number of electrons, protons, and neutrons. And each proton has the same mass as every other proton. Each electron has the same mass as every other electron. Each neutron has the same mass as every other neutron. Thus the mass of each atom, say a hydrogen atom, has the same mass as every other hydrogen atom. The same goes for all matter. Science measure mass according to how much force it takes to accelerate the matter. The matter resists being accelerated in an exact ratio to the number of elementary particles present. We use the word 'inertia' to describe this resistance to being accelerated. Thus, inertia is simply the resistance that all bodies exert against any force acting upon the body.
Newton's Third law of Motion: When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.
Assume we have a first body exerting a force on a second body. The second body exerts an equal force backward. Where does this second force come from? What causes this second force of the second body to exert itself against the first body? The answer is that our universe supplied this second force. We label it as resistance to motion. We label it inertia. And we measure it as the equal and opposite force caused by the first object.
In school, many are taught that inertia is a fictitious force. Educators awhile back started using the words 'fictitious force' as a descriptor for forces that arise in our universe seemingly out of nowhere, and which often go by different names such as pseudo force, d'Alembert force, and in the case we are discussing here, inertial force. These ‘apparent’ or 'fictitious' forces act on all material mass.
Eccentrically1, you called a unicorn as fictitious type of horse. Thus your concept of the word 'fictitious' is that it does not exist. In school you were taught that the above mentioned forces are 'fictitious forces', and because you know the meaning of a fictitious unicorn, you assume that a fictitious force does not exit. The reason that educator use the words 'fictitious' is because the forces having this handle don't arise directly, but come into being indirectly because the universe resists and pushes back whenever any material matter changes velocity, speed, or direction.
Unfortunately in your mind, you mix the fictitiousness of unicorns with the fictitiousness of inertia. And you claim that that inertia force or inertial resistance to force is fictitious in the same manner that a unicorn is fictitious.
The modern school system has warped the minds of younger students. A force is a push or pull. Inertial force is the pull of the universe counteracting the push of a known force whenever objects accelerate, decelerate, change speed, or change direction. Such forces are actual physical forces supplied by our universe in reaction to opposite forces.
Calling such forces 'fictitious' is confusing to young students. It puts in their minds that such forces are like unicorns and don't exist. It would be much better if the scientific world used a phrase like 'universe force' in describing such forces, but hey, they have chosen to use 'fictitious force'. Giving such forces the nomenclature of 'fictitious' does not magically make them into unicorn-type forces.
The bottom line is that inertia exists. It manifests itself in the resisting force produced by the universe in which we live, whenever any object changes velocity or direction. In other words, whenever any object accelerates or decelerates. When you measure the resisting force of inertia, it is equal to the change of momentum. It this sense, inertial force is the inverse of momentum force. If you truncate the phrase 'inertial force' to simply 'inertia' then it becomes the same as truncating the phrase 'momentum force' to simply 'momentum'. Momentum is mass times velocity. When the velocity is zero then you have just the mass with no velocity. Inertia is mass without the velocity. We don't assign any values to inertia because it is understood to be mass at zero velocity. So inertia becomes more of a concept than an actual quantity of physics. Instead, we use the word 'mass', which in reality is a measure of the inertial resistance of material being accelerated.
The bottom line... All Earthly materials exhibit resistance to change of motion. This resistance is often called inertia. Inertial force is the resisting force. Mass has two meanings which are often mixed. If you weigh an object on a scale you will say its weight measurement is a certain number of kilograms. This is a measure of its gravitational force caused by it physical mass. If you transport the object into outer space then its weight measurement drops to near zero. But its mass stays the same. It will still take the same force over a same distance to affect a same change of velocity as it does here on Earth. This resistance to change of motion is not momentum, though you might call it negative momentum. But we call it inertia. And inertia has an initial velocity component of zero speed. Thus inertia is simply zero momentum.
Inertial forces are NOT fictitious in the same sense a unicorns. It is unfortunate that educators and academician have chosen the word 'fictitious' when referring to forces derived from and supplied by the universe within which we live.
I'm going to scream the next time anyone claims that a force is not an actual force because some academician decided to label certain forces as being 'fictitious' and thus in some peoples mind they think such forces don't exist in the same sense that unicorns don't exits.
Sorry for such a long post. But when I truncate my writing it seems many don’t comprehend what I write. And if I let the words flow, I’m sure I’ve lost many reader after a few paragraphs.
