Op 16-nov.-2021 om 16:54 schreef Ed Lake:
> On Monday, November 15, 2021 at 3:26:04 PM UTC-6, rotchm wrote:
>> On Monday, November 15, 2021 at 3:59:42 PM UTC-5, wrote:
>>> Okay, now we're getting somewhere.
>> May I suggest that we then discuss one point, one topic at a time, as you suggested. Like, I suggest we discuss the definitions, the meanings of the words used. One needs to understand what he reads before going further.
>>
>> So I suggest first that we clear up the meaning of "inertial system" and try to agree on its definition.
>> From:https://en.wikipedia.org/wiki/Inertial_frame_of_reference
>> "...an inertial frame of reference is a frame of reference that is not undergoing acceleration. ".
>>
>> A truck coasting at constant speed of 50 miles per hour is not accelerating hence it is inertial (by this definition), agreed?
>>
>> And if you read on the definition from the wiki site (or any other reference), nowhere does it invoke the need to be a "propelled system".
>> Comment?
>
> Okay. Good point. I can see where you get your screwball beliefs.
> But a truck cannot COAST at a constant speed of 50 mph. If the
> driver's foot needs to be on the gas pedal to make that happen, then
> the truck is NOT "coasting."

Sub-infra-moron.

Dirk Vdm

On Tuesday, November 16, 2021 at 10:54:15 AM UTC-5, det...@outlook.com wrote:

> > And if you read on the definition from the wiki site (or any other reference), nowhere does it invoke the need to be a "propelled system".
> > Comment?
> Okay. Good point. I can see where you get your screwball beliefs.

They are not beliefs. They are the application of the definition.
Again, we are merely discussing the definition of inertial. We must agree on what the meaning, the definition means. This is a language problem. This is what we got to clear up first.

> But a truck cannot COAST at a constant speed of 50 mph. If the
> driver's foot needs to be on the gas pedal to make that happen, then
> the truck is NOT "coasting."

Yes it is. That is the meaning of "coasting".
Here coasting at 50 mph means, given all the "causes" of what is making a truck go, the net resulting effect it's that it is coasting at a constant speed of 50 mph, without any accelerations whatsoever. That is what meaning, that is what we meant, that is what the words mean.

> That wiki page also says, "Conceptually, the physics of a system in an
> inertial frame have no causes external to the system."

Exactly. Independently what causes the overall movement, the system in question is inertial.

> But a truck has many causes external to the system.

And as the Wiki page says, all that has nothing to do with the inertial system.

Again, in the truck coasting at constant speed relative to the ground, the system is not accelerating (to within the confines of our analysis).

On 11/16/2021 10:54 AM, Ed Lake wrote:
> On Monday, November 15, 2021 at 3:26:04 PM UTC-6, rotchm wrote:
>> On Monday, November 15, 2021 at 3:59:42 PM UTC-5, wrote:
>>> Okay, now we're getting somewhere.
>> May I suggest that we then discuss one point, one topic at a time, as you suggested. Like, I suggest we discuss the definitions, the meanings of the words used. One needs to understand what he reads before going further.
>>
>> So I suggest first that we clear up the meaning of "inertial system" and try to agree on its definition.
>> From:https://en.wikipedia.org/wiki/Inertial_frame_of_reference
>> "...an inertial frame of reference is a frame of reference that is not undergoing acceleration. ".
>>
>> A truck coasting at constant speed of 50 miles per hour is not accelerating hence it is inertial (by this definition), agreed?
>>
>> And if you read on the definition from the wiki site (or any other reference), nowhere does it invoke the need to be a "propelled system".
>> Comment?
>
> Okay. Good point. I can see where you get your screwball beliefs.

Those "screwball beliefs" come from Newton and Galileo.

> But a truck cannot COAST at a constant speed of 50 mph. If the
> driver's foot needs to be on the gas pedal to make that happen, then
> the truck is NOT "coasting."

Yet the reference doesn't invoke anything forbidding any "propelled
system" (by any wording) being inertial. Stating the truck is not
"coasting" is just another way for you to say "it's a propelled system
and that can't be inertial!" without the words "propelled system".
There is no language forbidding inertial "propelled systems" with any
wording.
>
> That wiki page also says, "Conceptually, the physics of a system in an
> inertial frame have no causes external to the system."

It needs to be worded better. The external "causes" (forces) must sum
to zero, just like Newton said. Not completely absent, but sum to zero.
>
> But a truck has many causes external to the system. According to Odds
> Bodkin in the previous message, "There are
> indeed at least four forces acting on the car (air resistance pushing
> backwards, the friction between the tires and the road surface pushing the
> car forward — that’s where the engine comes in, the force of gravity
> downwards, and the force of the road pushing upward),"

Again, what is necessary for something to be inertial is no
acceleration. The sum of the forces must be zero. That's it. See
Newton and Galileo. This was settled science hundreds of years ago.
>
> It seems to me that you can recite memorized words you learned in
> school, but you do not understand what they mean in our real world.

It is you who can't seem to understand Galilean relativity, of no
absolute reference frame.

Michael Moroney wrote:

> His inertial system isn't perfectly inertial either. The earth is
> rotating (not inertial), revolving around the sun (not inertial), wind
> is still blowing, he's moving around somewhat (whether in the cruiser or
> standing with a handheld unit), vibrations from passing vehicles etc.

nonsense, the constant speed is inertial.

Pfizer is the Largest Criminal Company in the World, *official*
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Ed Lake <detect@outlook.com> wrote:
> On Monday, November 15, 2021 at 3:24:59 PM UTC-6, bodk...@gmail.com wrote:
>> Ed Lake wrote:
>>> Okay, now we're getting somewhere. You have all made it abundantly clear
>>> that you have ABSOLUTELY NO COMPREHENSION of how reality relates
>>> to mathematics. All you know is mathematics.
>>>
>>> Let's discuss reality.
>>>
>>> We have a truck traveling at 50 miles per hour on Interstate 94 between
>>> Chicago, Illinois, and Kenosha, Wisconsin.
>>>
>>> The truck runs out of gas, and the truck slows to a stop at the side of the road.
>>>
>>> According to the mathematicians on this forum, the truck will just as likely
>>> end up on Mars or Alpha Centauri or some spot in the Andromeda Galaxy.
>>> You cannot comprehend that friction will bring it to a stop on Interstate 94.
>> No, that’s not the statement at all.
>> Here is the statement.
>>
>> While the car engine and is engaged, and the car is traveling a constant 80
>> mph on a straight and flat road, it is in inertial motion. It is in
>> inertial motion because there is NO NET force acting on the car. There are
>> indeed at least four forces acting on the car (air resistance pushing
>> backwards, the friction between the tires and the road surface pushing the
>> car forward — that’s where the engine comes in, the force of gravity
>> downwards, and the force of the road pushing upward), but these forces all
>> sum to zero and there is no net force. This net force being zero also means
>> there is no acceleration (that’s Newton’s 2nd law), and since the
>> acceleration is zero, the velocity is constant. That is inertial motion: no
>> NET force, no acceleration, constant velocity.
>>
>> Now you put the car in neutral and turn the engine off. Now there is a net
>> force on the car because the air resistance is still there pushing
>> backwards but there is no force pushing forwards. Because there is a net
>> force, there is also an acceleration, and the car slows down. While it is
>> slowing down, it is no longer in inertial motion. (Notice that there is no
>> propulsion anymore, but there is a net force, so it is not inertial
>> motion.)
>>
>> Now the car comes to a STOP on the road, and of course the air resistance
>> goes away. So, once again, there is no NET force on the car, and so there
>> is no acceleration, and so the velocity with respect to the road is
>> constant. Of course it’s constant; it’s zero. It is once again in inertial
>> motion.
>>
>> So in the exercise we just talked about, there are TWO instances of
>> inertial motion, one where the car is traveling at a constant 80 mph on a
>> straight and flat road (and so you see it being propelled doesn’t change
>> that), and one where it is at rest at a constant 0 mph on a straight and
>> flat road (and so the lack of propulsion has nothing to do with that).
>>
>> Everything that I just described to you is taught in freshman level
>> physics, in plain language, so that students will understand what inertial
>> motion is.
>>
>> You, however, have decided in your infinite wisdom that inertial motion
>> must mean something like “at rest relative to the nearest unpropelled
>> massive body, such as the earth’s surface”. It doesn’t mean anything like
>> that at all. It means what I said it means above, which you can actually
>> check for yourself by READING a freshman physics text, rather than just
>> trying to sort this all out in your own head.
>
> Okay. Very interesting.

Well, I’m glad it’s interesting to you. It is also BASIC first year
physics. I would encourage you to spend more time learning first year
physics, because maybe you will find the BASICS to be all very, very
interesting.

> So, when a truck is being propelled at a constant
> 80 mph down I-94, it is an inertial system.

Yes.

> You realize, of course, that the
> truck is bumping over cracks in the pavement, it is being pushed by winds, the
> truck driver's foot on the gas pedal is not perfectly steady, so the speed
> actually varies a bit up and down. And yet you believe it is an inertial
> system.

Well, what you are encountering is ANOTHER basic in physics, which is
called the idealization that happens in modeling. You will see examples
worked out in freshman texts about parabolic trajectories of projectiles,
where it is advised to “ignore friction”. Why ignore friction when it is
present? There are lots of reasons. First, the point is to illustrate that
the principle applies and is successful, even if there are additional
factors present outside the principle. Second, whether those secondary
effects are significant depends on their size and the precision of the
measurement; if an effect is present but yields a perturbation that is
smaller than the measurement precision, then it is rightfully IGNORABLE in
a physics analysis of that system. Third, the point of modeling of physical
systems is to find simple methods that describe a wide variety of physical
systems, which is a focus on those things where they are dominantly common
where you can safely neglect all the little ways they are different. This
is why you can treat so many things as simple harmonic oscillators, even
though all those things vary in little ways that make them both not IDEAL
simple oscillators but also different from each other. And to give you a
sense of scope, SHOs do well describe everything from alternating current
circuits to suspension bridge cables to piezoelectric crystals to ocean
waves to guitar strings.

I wish to reiterate that this lesson about physical modeling is FIRST YEAR
physics, something that you should have a grip on BEFORE you start thinking
about more advanced topics.

>
> And a police officer, who is standing on A DIFFERENT inertial system,
> the earth, can point a radar gun at the truck and measure the truck's speed.
>
> I'd say that your BELIEF as to what constitutes an "inertial system" is
> just that, your BELIEF. It doesn't have anything to do with reality.

Ed, I’ll again reiterate that if a jargon term like “inertial system” is
carefully described in all physics textbooks by physicists, and you believe
that your made-up meaning for the same term is correct and all the
physicists’ meaning for term is completely wrong, then you are stepping
boldly and firmly into crazy crackpot territory. This is especially true if
it turns out you’ve never bothered to LOOK at what physicists say the term
means in physics textbooks, but just decided to figure out what it must
mean just by “thinking about it”.

This was made abundantly clear when you responded to my explanation of the
car on the road and what initial motion means in that context. I gave you
essentially the same content that you would have obtained by READING a
first year book, and you responded with “interesting”, as you’d clearly
never heard of it before. And look at how you responded. Instead of
absorbing something you didn’t know before as useful information, you
decided to tip over the checkers board and walk away. You’d much rather
DISMISS a basic lesson and cling to your own idea, than to learn something
new. This is a personality problem, something you’ll find will prevent you
from understanding anything new. Contention is not a viable learning tool.

>
> Ed
>

--
Odd Bodkin -- maker of fine toys, tools, tables

On Tuesday, November 16, 2021 at 9:55:26 AM UTC-6, Paparios wrote:
> El martes, 16 de noviembre de 2021 a las 12:41:12 UTC-3, escribió:
> > On Monday, November 15, 2021 at 3:24:59 PM UTC-6, bodk...@gmail.com wrote:
>
> > > You, however, have decided in your infinite wisdom that inertial motion
> > > must mean something like “at rest relative to the nearest unpropelled
> > > massive body, such as the earth’s surface”. It doesn’t mean anything like
> > > that at all. It means what I said it means above, which you can actually
> > > check for yourself by READING a freshman physics text, rather than just
> > > trying to sort this all out in your own head.
>
> > Okay. Very interesting. So, when a truck is being propelled at a constant
> > 80 mph down I-94, it is an inertial system. You realize, of course, that the
> > truck is bumping over cracks in the pavement, it is being pushed by winds, the
> > truck driver's foot on the gas pedal is not perfectly steady, so the speed
> > actually varies a bit up and down. And yet you believe it is an inertial
> > system.
> >
> > And a police officer, who is standing on A DIFFERENT inertial system,
> > the earth, can point a radar gun at the truck and measure the truck's speed.
> >
> > I'd say that your BELIEF as to what constitutes an "inertial system" is
> > just that, your BELIEF. It doesn't have anything to do with reality.
> >
> > Ed
> It is not a belief. It is what physicists have defined as inertial systems:
>
> "In classical physics and special relativity, an inertial frame of reference is a frame of reference that is not undergoing acceleration. In an inertial frame of reference, a physical object with zero net force acting on it moves with a constant velocity (which might be zero)—or, equivalently, it is a frame of reference in which Newton's first law of motion holds.. An inertial frame of reference can be defined in analytical terms as a frame of reference that describes time and space homogeneously, isotropically, and in a time-independent manner. Conceptually, the physics of a system in an inertial frame have no causes external to the system. An inertial frame of reference may also be called an inertial reference frame, inertial frame, Galilean reference frame, or inertial space.
>
> All inertial frames are in a state of constant, rectilinear motion with respect to one another; an accelerometer moving with any of them would detect zero acceleration. Measurements in one inertial frame can be converted to measurements in another by a simple transformation (the Galilean transformation in Newtonian physics and the Lorentz transformation in special relativity). In general relativity, in any region small enough for the curvature of spacetime and tidal forces to be negligible, one can find a set of inertial frames that approximately describe that region".
>
> You need to study a lot more!!!!

Yes, studying would help me figure out where you get your screwball
ideas.

The word "accelerating" seems to be the issue today. You all argue that
a truck traveling at a steady 50 mph is "NOT ACCELERATING," and therefore
it is an "inertial system." In theory that may be true, but in real life it is NOT.
In real life, the truck driver has to keep his foot on the accelerator in order
to maintain 50 mph. And if the speedometer was more precise, we would
see that the speed is NOT CONSTANT, but varies between 49 and 51 mph
because of external factors, like cracks in the road and varying wind resistance.

But the key issue is what a radar gun will measure. That is what our main
conflict is all about.

There is no disagreement that a cop standing at the side of the road will
measure 50 mph for the truck when he uses his radar gun. There IS a
disagreement over how his radar gun works. I say his radar gun
will emit photons at c which hit the truck at c+v, where v is the speed of
the truck. The truck emits photons back to the radar gun that have the
c+v energy. The gun compares the energy of the photons it emitted to
the energy of the photons that returned, and computes a speed of 50 mph
for the truck.

So, the cop is on one inertial system (the earth) and, according to people
here, he is measuring the speed of another inertial system, the truck.

He measures a speed of 50 mph.

Another issue is what would that cop measure if he was INSIDE the truck?
Answer: He would measure a speed of zero. Why? Because his radar gun
would emit photons at c that hit the real wall of the truck at c+v, then atoms
in the wall emit photons back to the gun at c that hit the gun at c-v. The
gun then computes c+v-v=c and gets a speed of zero .

My proposed experiment would eliminate one of those two measurements.
If you have TWO radar guns with IDENTICAL frequencies pointed at each
other, each gun would emit photons at c that hit the other gun at either
c+v or c-v. Each gun would receive the photons from the other gun as if
they were returning from a target. Radar guns show the fastest measured
speed, so, instead of showing zero, one gun will show +50 mph and the
other gun will show -50 mph.

You all claim this is impossible, because the truck is an inertial system."
I say it is a "propelled system." I cannot call it an "accelerating" system
because the word "accelerate" means "to cause to increase speed." In
reality, the truck is constantly accelerating and decelerating in order to
maintain a steady speed.

The only way I see out of this dilemma is for people here to understand
that photons EMITTED at c hit a moving OBSERVER at c+v or c-v where
v is the speed of the observer toward or away from the emitter. That is
what MANY EXPERIMENTS show. I list and describe those experiments
here: www.ed-lake.com/Speed-of-received-light.html

Ed

Ed Lake <detect@outlook.com> wrote:
> On Monday, November 15, 2021 at 3:26:04 PM UTC-6, rotchm wrote:
>> On Monday, November 15, 2021 at 3:59:42 PM UTC-5, wrote:
>>> Okay, now we're getting somewhere.
>> May I suggest that we then discuss one point, one topic at a time, as
>> you suggested. Like, I suggest we discuss the definitions, the meanings
>> of the words used. One needs to understand what he reads before going further.
>>
>> So I suggest first that we clear up the meaning of "inertial system" and
>> try to agree on its definition.
>> From:https://en.wikipedia.org/wiki/Inertial_frame_of_reference
>> "...an inertial frame of reference is a frame of reference that is not
>> undergoing acceleration. ".
>>
>> A truck coasting at constant speed of 50 miles per hour is not
>> accelerating hence it is inertial (by this definition), agreed?
>>
>> And if you read on the definition from the wiki site (or any other
>> reference), nowhere does it invoke the need to be a "propelled system".
>> Comment?
>
> Okay. Good point. I can see where you get your screwball beliefs.
> But a truck cannot COAST at a constant speed of 50 mph. If the
> driver's foot needs to be on the gas pedal to make that happen, then
> the truck is NOT "coasting."

This depends on the meaning of “coasting”, which is not a physics term. It
can mean cruising at constant speed (which means having a foot on the
accelerator), or it can mean moving unpowered (which would mean not only
having a foot off the accelerator, but also the transmission in neutral or
the clutch disengaged). This is the problem with colloquial language. It
is ambiguous and opens the door to crossed communications. Physics jargon,
like “inertial motion”, is completely different and much, much less
ambiguity is there.

>
> That wiki page also says, "Conceptually, the physics of a system in an
> inertial frame have no causes external to the system."
>
> But a truck has many causes external to the system. According to Odds
> Bodkin in the previous message, "There are
> indeed at least four forces acting on the car (air resistance pushing
> backwards, the friction between the tires and the road surface pushing the
> car forward — that’s where the engine comes in, the force of gravity
> downwards, and the force of the road pushing upward),"

Yes, but it is still true in an inertial system that all the forces sum to
zero, no matter how you count them up, to the precision relevant to the
analysis. I listed the non transient and large ones. Wind gusts are not of
that category.

>
> It seems to me that you can recite memorized words you learned in
> school, but you do not understand what they mean in our real world.
>
> Ed
>

--
Odd Bodkin -- maker of fine toys, tools, tables

Ed Lake wrote:

>> You need to study a lot more!!!!
>
> Yes, studying would help me figure out where you get your screwball
> ideas.
> The word "accelerating" seems to be the issue today. You all argue that
> a truck traveling at a steady 50 mph is "NOT ACCELERATING," and
> therefore it is an "inertial system." In theory that may be true, but
> in real life it is NOT.

yes, but

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Vaccine Trials Are Not Public!
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Ed Lake <detect@outlook.com> wrote:
> On Tuesday, November 16, 2021 at 9:55:26 AM UTC-6, Paparios wrote:
>> El martes, 16 de noviembre de 2021 a las 12:41:12 UTC-3, escribió:
>>> On Monday, November 15, 2021 at 3:24:59 PM UTC-6, bodk...@gmail.com wrote:
>>
>>>> You, however, have decided in your infinite wisdom that inertial motion
>>>> must mean something like “at rest relative to the nearest unpropelled
>>>> massive body, such as the earth’s surface”. It doesn’t mean anything like
>>>> that at all. It means what I said it means above, which you can actually
>>>> check for yourself by READING a freshman physics text, rather than just
>>>> trying to sort this all out in your own head.
>>
>>> Okay. Very interesting. So, when a truck is being propelled at a constant
>>> 80 mph down I-94, it is an inertial system. You realize, of course, that the
>>> truck is bumping over cracks in the pavement, it is being pushed by winds, the
>>> truck driver's foot on the gas pedal is not perfectly steady, so the speed
>>> actually varies a bit up and down. And yet you believe it is an inertial
>>> system.
>>>
>>> And a police officer, who is standing on A DIFFERENT inertial system,
>>> the earth, can point a radar gun at the truck and measure the truck's speed.
>>>
>>> I'd say that your BELIEF as to what constitutes an "inertial system" is
>>> just that, your BELIEF. It doesn't have anything to do with reality.
>>>
>>> Ed
>> It is not a belief. It is what physicists have defined as inertial systems:
>>
>> "In classical physics and special relativity, an inertial frame of
>> reference is a frame of reference that is not undergoing acceleration.
>> In an inertial frame of reference, a physical object with zero net force
>> acting on it moves with a constant velocity (which might be zero)—or,
>> equivalently, it is a frame of reference in which Newton's first law of
>> motion holds. An inertial frame of reference can be defined in
>> analytical terms as a frame of reference that describes time and space
>> homogeneously, isotropically, and in a time-independent manner.
>> Conceptually, the physics of a system in an inertial frame have no
>> causes external to the system. An inertial frame of reference may also
>> be called an inertial reference frame, inertial frame, Galilean
>> reference frame, or inertial space.
>>
>> All inertial frames are in a state of constant, rectilinear motion with
>> respect to one another; an accelerometer moving with any of them would
>> detect zero acceleration. Measurements in one inertial frame can be
>> converted to measurements in another by a simple transformation (the
>> Galilean transformation in Newtonian physics and the Lorentz
>> transformation in special relativity). In general relativity, in any
>> region small enough for the curvature of spacetime and tidal forces to
>> be negligible, one can find a set of inertial frames that approximately
>> describe that region".
>>
>> You need to study a lot more!!!!
>
> Yes, studying would help me figure out where you get your screwball
> ideas.
>
> The word "accelerating" seems to be the issue today. You all argue that
> a truck traveling at a steady 50 mph is "NOT ACCELERATING," and therefore
> it is an "inertial system." In theory that may be true, but in real life it is NOT.
> In real life, the truck driver has to keep his foot on the accelerator in order
> to maintain 50 mph.

Keeping your foot on the accelerator does not mean you are accelerating.
The proper name for that pedal is a throttle, not an accelerator.

> And if the speedometer was more precise, we would
> see that the speed is NOT CONSTANT, but varies between 49 and 51 mph
> because of external factors, like cracks in the road and varying wind resistance.

Sure, but those are often small enough effects to say that, for the
purposes of modeling, the sum of the forces is treatable as zero. This is
basic idealization in scientific modeling, which is taught in HIGH SCHOOL
science.

>
> But the key issue is what a radar gun will measure. That is what our main
> conflict is all about.
>
> There is no disagreement that a cop standing at the side of the road will
> measure 50 mph for the truck when he uses his radar gun. There IS a
> disagreement over how his radar gun works. I say his radar gun
> will emit photons at c which hit the truck at c+v, where v is the speed of
> the truck. The truck emits photons back to the radar gun that have the
> c+v energy. The gun compares the energy of the photons it emitted to
> the energy of the photons that returned, and computes a speed of 50 mph
> for the truck.
>
> So, the cop is on one inertial system (the earth) and, according to people
> here, he is measuring the speed of another inertial system, the truck.
>
> He measures a speed of 50 mph.
>
> Another issue is what would that cop measure if he was INSIDE the truck?
> Answer: He would measure a speed of zero. Why? Because his radar gun
> would emit photons at c that hit the real wall of the truck at c+v, then atoms
> in the wall emit photons back to the gun at c that hit the gun at c-v. The
> gun then computes c+v-v=c and gets a speed of zero .
>
> My proposed experiment would eliminate one of those two measurements.
> If you have TWO radar guns with IDENTICAL frequencies pointed at each
> other, each gun would emit photons at c that hit the other gun at either
> c+v or c-v. Each gun would receive the photons from the other gun as if
> they were returning from a target. Radar guns show the fastest measured
> speed, so, instead of showing zero, one gun will show +50 mph and the
> other gun will show -50 mph.
>
> You all claim this is impossible, because the truck is an inertial system."
> I say it is a "propelled system." I cannot call it an "accelerating" system
> because the word "accelerate" means "to cause to increase speed." In
> reality, the truck is constantly accelerating and decelerating in order to
> maintain a steady speed.
>
> The only way I see out of this dilemma is for people here to understand
> that photons EMITTED at c hit a moving OBSERVER at c+v or c-v where
> v is the speed of the observer toward or away from the emitter. That is
> what MANY EXPERIMENTS show. I list and describe those experiments
> here: www.ed-lake.com/Speed-of-received-light.html
>
> Ed
>

--
Odd Bodkin -- maker of fine toys, tools, tables

On 11/16/2021 11:50 AM, Ed Lake wrote:
> On Tuesday, November 16, 2021 at 9:55:26 AM UTC-6, Paparios wrote:
>> El martes, 16 de noviembre de 2021 a las 12:41:12 UTC-3, escribió:
>>> On Monday, November 15, 2021 at 3:24:59 PM UTC-6, bodk...@gmail.com wrote:
>>
>>>> You, however, have decided in your infinite wisdom that inertial motion
>>>> must mean something like “at rest relative to the nearest unpropelled
>>>> massive body, such as the earth’s surface”. It doesn’t mean anything like
>>>> that at all. It means what I said it means above, which you can actually
>>>> check for yourself by READING a freshman physics text, rather than just
>>>> trying to sort this all out in your own head.
>>
>>> Okay. Very interesting. So, when a truck is being propelled at a constant
>>> 80 mph down I-94, it is an inertial system. You realize, of course, that the
>>> truck is bumping over cracks in the pavement, it is being pushed by winds, the
>>> truck driver's foot on the gas pedal is not perfectly steady, so the speed
>>> actually varies a bit up and down. And yet you believe it is an inertial
>>> system.
>>>
>>> And a police officer, who is standing on A DIFFERENT inertial system,
>>> the earth, can point a radar gun at the truck and measure the truck's speed.
>>>
>>> I'd say that your BELIEF as to what constitutes an "inertial system" is
>>> just that, your BELIEF. It doesn't have anything to do with reality.
>>>
>>> Ed
>> It is not a belief. It is what physicists have defined as inertial systems:
>>
>> "In classical physics and special relativity, an inertial frame of reference is a frame of reference that is not undergoing acceleration. In an inertial frame of reference, a physical object with zero net force acting on it moves with a constant velocity (which might be zero)—or, equivalently, it is a frame of reference in which Newton's first law of motion holds. An inertial frame of reference can be defined in analytical terms as a frame of reference that describes time and space homogeneously, isotropically, and in a time-independent manner. Conceptually, the physics of a system in an inertial frame have no causes external to the system. An inertial frame of reference may also be called an inertial reference frame, inertial frame, Galilean reference frame, or inertial space.
>>
>> All inertial frames are in a state of constant, rectilinear motion with respect to one another; an accelerometer moving with any of them would detect zero acceleration. Measurements in one inertial frame can be converted to measurements in another by a simple transformation (the Galilean transformation in Newtonian physics and the Lorentz transformation in special relativity). In general relativity, in any region small enough for the curvature of spacetime and tidal forces to be negligible, one can find a set of inertial frames that approximately describe that region".
>>
>> You need to study a lot more!!!!
>
> Yes, studying would help me figure out where you get your screwball
> ideas.

Newton and Galileo.

That are the DEFINITION of inertial frames. You can't make up your own
definition and say the actual definition is wrong according to YOUR
definition.
>
> The word "accelerating" seems to be the issue today. You all argue that
> a truck traveling at a steady 50 mph is "NOT ACCELERATING," and therefore
> it is an "inertial system." In theory that may be true, but in real life it is NOT.
> In real life, the truck driver has to keep his foot on the accelerator in order
> to maintain 50 mph. And if the speedometer was more precise, we would
> see that the speed is NOT CONSTANT, but varies between 49 and 51 mph
> because of external factors, like cracks in the road and varying wind resistance.

I already addressed that. It is "inertial enough", such errors are too
small to affect things. Especially since gedankens assume ideal
conditions, the road is perfectly smooth and level, the truck has a
perfect cruise control system etc. Your nitpicks are a desperation measure.
>
> But the key issue is what a radar gun will measure. That is what our main
> conflict is all about.
>
> There is no disagreement that a cop standing at the side of the road will
> measure 50 mph for the truck when he uses his radar gun. There IS a
> disagreement over how his radar gun works.

Not really a "disagreement", it is just your beliefs against all the
scientists and engineers working with radar and related fields.

> I say his radar gun
> will emit photons at c which hit the truck at c+v, where v is the speed of
> the truck.

What you say is wrong. Once again, photons striking the truck at c+v
violates the second postulate, so your "Laketons" aren't compatible with
relativity.

> The truck emits photons back to the radar gun that have the
> c+v energy.

You mean the Doppler shifted frequency of the microwaves, of course.

> The gun compares the energy of the photons it emitted to
> the energy of the photons that returned,

Once again, radar guns don't compare energy of photons, Laketons or
anything else. The received microwave signal is converted into an
electronic signal by the antenna. This signal (which is no longer
photons) has a frequency, which is compared to the original transmitted
frequency. This is another signal, electronic current which is not
photons, and was NEVER photons, EVER. The circuitry calculates the
difference in frequencies of the AC electric signals (not photons) and
the frequency difference is proportional to the speed difference.

> and computes a speed of 50 mph
> for the truck.
>
> So, the cop is on one inertial system (the earth) and, according to people
> here, he is measuring the speed of another inertial system, the truck.
>
> He measures a speed of 50 mph.
>
> Another issue is what would that cop measure if he was INSIDE the truck?
> Answer: He would measure a speed of zero. Why?

Because the returned signal is the same frequency as the transmitted
signal because the gun and truck wall are all stationary in a certain
frame of reference.

> Because his radar gun
> would emit photons at c that hit the real wall of the truck at c+v,

Ignoring the second postulate violation, why would the frame used jump
to the road frame here?

> then atoms
> in the wall emit photons back to the gun at c that hit the gun at c-v.

And why did you switch back to the truck frame again?

> The
> gun then computes c+v-v=c

Nope, because of time of travel, "c+v-c" really is sqrt(c^2-v^2), always
less than c.

> and gets a speed of zero .

Nope.
>
> My proposed experiment would eliminate one of those two measurements.
> If you have TWO radar guns with IDENTICAL frequencies pointed at each
> other, each gun would emit photons at c that hit the other gun at either
> c+v or c-v.

How are the guns moving? Apparently one at v relative to the other?

> Each gun would receive the photons from the other gun as if
> they were returning from a target. Radar guns show the fastest measured
> speed, so, instead of showing zero, one gun will show +50 mph and the
> other gun will show -50 mph.

The only way this would happen is if one gun was alongside the road and
the other gun was moving in the truck, aimed through the windshield or
something.
>
> You all claim this is impossible, because the truck is an inertial system."
> I say it is a "propelled system."

It IS an inertial system, by the definition of an inertial system.

> I cannot call it an "accelerating" system
> because the word "accelerate" means "to cause to increase speed."

You got something correct for once.
Since it is not an accelerating system, it is an inertial system.

> In
> reality, the truck is constantly accelerating and decelerating in order to
> maintain a steady speed.

Your nitpicks are a sign of desperation, as I already said.
>
> The only way I see out of this dilemma

No dilemma, except in your mind.

> is for people here to understand
> that photons EMITTED at c hit a moving OBSERVER at c+v or c-v where
> v is the speed of the observer toward or away from the emitter.

Why do you think people should disregard the second postulate?

> That is
> what MANY EXPERIMENTS show.

No experiments show that.

> I list and describe those experiments
> here: www.ed-lake.com/Speed-of-received-light.html

All full of the same errors I already pointed out.

You couldn't pass high school physics with those mistakes.

On Tuesday, November 16, 2021 at 10:55:52 AM UTC-6, bodk...@gmail.com wrote:
> Ed Lake wrote:
> > On Monday, November 15, 2021 at 3:26:04 PM UTC-6, rotchm wrote:
> >> On Monday, November 15, 2021 at 3:59:42 PM UTC-5, wrote:
> >>> Okay, now we're getting somewhere.
> >> May I suggest that we then discuss one point, one topic at a time, as
> >> you suggested. Like, I suggest we discuss the definitions, the meanings
> >> of the words used. One needs to understand what he reads before going further.
> >>
> >> So I suggest first that we clear up the meaning of "inertial system" and
> >> try to agree on its definition.
> >> From:https://en.wikipedia.org/wiki/Inertial_frame_of_reference
> >> "...an inertial frame of reference is a frame of reference that is not
> >> undergoing acceleration. ".
> >>
> >> A truck coasting at constant speed of 50 miles per hour is not
> >> accelerating hence it is inertial (by this definition), agreed?
> >>
> >> And if you read on the definition from the wiki site (or any other
> >> reference), nowhere does it invoke the need to be a "propelled system"..
> >> Comment?
> >
> > Okay. Good point. I can see where you get your screwball beliefs.
> > But a truck cannot COAST at a constant speed of 50 mph. If the
> > driver's foot needs to be on the gas pedal to make that happen, then
> > the truck is NOT "coasting."
> This depends on the meaning of “coasting”, which is not a physics term. It
> can mean cruising at constant speed (which means having a foot on the
> accelerator), or it can mean moving unpowered (which would mean not only
> having a foot off the accelerator, but also the transmission in neutral or
> the clutch disengaged). This is the problem with colloquial language. It
> is ambiguous and opens the door to crossed communications. Physics jargon,
> like “inertial motion”, is completely different and much, much less
> ambiguity is there.
> >
> > That wiki page also says, "Conceptually, the physics of a system in an
> > inertial frame have no causes external to the system."
> >
> > But a truck has many causes external to the system. According to Odds
> > Bodkin in the previous message, "There are
> > indeed at least four forces acting on the car (air resistance pushing
> > backwards, the friction between the tires and the road surface pushing the
> > car forward — that’s where the engine comes in, the force of gravity
> > downwards, and the force of the road pushing upward),"
> Yes, but it is still true in an inertial system that all the forces sum to
> zero, no matter how you count them up, to the precision relevant to the
> analysis. I listed the non transient and large ones. Wind gusts are not of
> that category.

Newton's first law of motion is: "An object at rest remains at rest, and an
object in motion remains in motion at constant speed and in a straight line
unless acted on by an unbalanced force."

An "inertial system" is defined as "a frame of reference in which a body
remains at rest or moves with constant linear velocity unless acted upon
by forces."

Since we are talking about a truck moving on the curved surface of the
earth, that definition of "inertial system" does not apply.

The idea that a moving truck can be an "inertial system" is just IDIOTIC
to me. FORCE makes the truck move. It is the driver's foot that causes
FORCE to be applied to the truck to cause it to move at APPROXIMATELY
50 mph. There is "NO BALANCE OF FORCES," there is just STEADY FORCE.

We seem to have irreconcilable differences. So, there is no point in
continuing on any discussion about inertia.

So, I'm done here --- unless someone addresses the FACT that light will
hit a moving observer at c+v or c-v.

Ed

On Tuesday, November 16, 2021 at 12:21:48 PM UTC-5, det...@outlook.com wrote:

> An "inertial system" is defined as "a frame of reference in which a body
> remains at rest or moves with constant linear velocity unless acted upon
> by forces."
>
> Since we are talking about a truck moving on the curved surface of the
> earth, that definition of "inertial system" does not apply.

Yes it does apply. Again, we are discussing inertial system (inertial motion) to within the *confines of the discussion*, the *setup*, to within our desired accuracies. When we say that the truck is coasting at 50mph, we mean that all the little vibrations, shape of the earth, etc are too small and insignificant for *our* purposes. We all have been telling you this. Do you realize it now?

So now, do you agree that a truck coasting at 50 mph is an inertial system?

> We seem to have irreconcilable differences. So, there is no point in
> continuing on any discussion about inertia.

We are not discussing inertia. We are discussing inertial systems, inertial motion. We must continue to discuss this, the meaning of the words, before we discuss further.

> So, I'm done here ---

No you are not. You agreed to discuss first the meaning of the words. We have not resolved that yet. So we must continue. Do not coward away. Be honest and finish the discussion you proposed. Recall you proposed discussing only one topic. And the topic we have been discussing is the meaning of the words used. In particular, inertial system.

El martes, 16 de noviembre de 2021 a las 13:50:14 UTC-3, det...@outlook.com escribió:
> On Tuesday, November 16, 2021 at 9:55:26 AM UTC-6, Paparios wrote:

> > You need to study a lot more!!!!
> Yes, studying would help me figure out where you get your screwball
> ideas.
>
> The word "accelerating" seems to be the issue today. You all argue that
> a truck traveling at a steady 50 mph is "NOT ACCELERATING," and therefore
> it is an "inertial system." In theory that may be true, but in real life it is NOT.
> In real life, the truck driver has to keep his foot on the accelerator in order
> to maintain 50 mph. And if the speedometer was more precise, we would
> see that the speed is NOT CONSTANT, but varies between 49 and 51 mph
> because of external factors, like cracks in the road and varying wind resistance.
>

As somebody wrote above, the acceleration (or not acceleration) can be easily measured by using an accelerometer. If the accelerometer indicates 0, it means the truck is an inertial system, period!!!

> But the key issue is what a radar gun will measure. That is what our main
> conflict is all about.
>
> There is no disagreement that a cop standing at the side of the road will
> measure 50 mph for the truck when he uses his radar gun. There IS a
> disagreement over how his radar gun works. I say his radar gun
> will emit photons at c which hit the truck at c+v, where v is the speed of
> the truck. The truck emits photons back to the radar gun that have the
> c+v energy. The gun compares the energy of the photons it emitted to
> the energy of the photons that returned, and computes a speed of 50 mph
> for the truck.
>

What any radar engineer would say is that if the cop radar gun emits a frequency fo and if the detected reflected received signal is fr, then the speed is given by v=(fr-fo)c/2fo, period!!!!

> So, the cop is on one inertial system (the earth) and, according to people
> here, he is measuring the speed of another inertial system, the truck.
>
> He measures a speed of 50 mph.
>
> Another issue is what would that cop measure if he was INSIDE the truck?
> Answer: He would measure a speed of zero. Why? Because his radar gun
> would emit photons at c that hit the real wall of the truck at c+v, then atoms
> in the wall emit photons back to the gun at c that hit the gun at c-v. The
> gun then computes c+v-v=c and gets a speed of zero .
>

What any radar engineer would say, in that case, is that if the cop radar gun emits a frequency fo and if the detected reflected received signal is fr=fo, then the speed is given by v=(fr-fo)c/2fo=0, period!!!!

> My proposed experiment would eliminate one of those two measurements.
> If you have TWO radar guns with IDENTICAL frequencies pointed at each
> other, each gun would emit photons at c that hit the other gun at either
> c+v or c-v. Each gun would receive the photons from the other gun as if
> they were returning from a target. Radar guns show the fastest measured
> speed, so, instead of showing zero, one gun will show +50 mph and the
> other gun will show -50 mph.
>

If you do that experiment, you will convince yourself that both radar guns will show v=0, for the very simple reason that the walls of the truck are not moving with respect to the other walls!!!!

> You all claim this is impossible, because the truck is an inertial system.."
> I say it is a "propelled system." I cannot call it an "accelerating" system
> because the word "accelerate" means "to cause to increase speed." In
> reality, the truck is constantly accelerating and decelerating in order to
> maintain a steady speed.
>

That is completely wrong, as any school student would understand. The truck keeps its speed (assuming the road is leveled) by the engine producing the truck wheels to compensate the friction between the truck tires and the pavement. That way, the truck maintains a constant speed. The minimal speed variations are irrelevant to the measurement error of the radar gun!!!

Ed Lake <detect@outlook.com> wrote:
> On Tuesday, November 16, 2021 at 10:55:52 AM UTC-6, bodk...@gmail.com wrote:
>> Ed Lake wrote:
>>> On Monday, November 15, 2021 at 3:26:04 PM UTC-6, rotchm wrote:
>>>> On Monday, November 15, 2021 at 3:59:42 PM UTC-5, wrote:
>>>>> Okay, now we're getting somewhere.
>>>> May I suggest that we then discuss one point, one topic at a time, as
>>>> you suggested. Like, I suggest we discuss the definitions, the meanings
>>>> of the words used. One needs to understand what he reads before going further.
>>>>
>>>> So I suggest first that we clear up the meaning of "inertial system" and
>>>> try to agree on its definition.
>>>> From:https://en.wikipedia.org/wiki/Inertial_frame_of_reference
>>>> "...an inertial frame of reference is a frame of reference that is not
>>>> undergoing acceleration. ".
>>>>
>>>> A truck coasting at constant speed of 50 miles per hour is not
>>>> accelerating hence it is inertial (by this definition), agreed?
>>>>
>>>> And if you read on the definition from the wiki site (or any other
>>>> reference), nowhere does it invoke the need to be a "propelled system".
>>>> Comment?
>>>
>>> Okay. Good point. I can see where you get your screwball beliefs.
>>> But a truck cannot COAST at a constant speed of 50 mph. If the
>>> driver's foot needs to be on the gas pedal to make that happen, then
>>> the truck is NOT "coasting."
>> This depends on the meaning of “coasting”, which is not a physics term. It
>> can mean cruising at constant speed (which means having a foot on the
>> accelerator), or it can mean moving unpowered (which would mean not only
>> having a foot off the accelerator, but also the transmission in neutral or
>> the clutch disengaged). This is the problem with colloquial language. It
>> is ambiguous and opens the door to crossed communications. Physics jargon,
>> like “inertial motion”, is completely different and much, much less
>> ambiguity is there.
>>>
>>> That wiki page also says, "Conceptually, the physics of a system in an
>>> inertial frame have no causes external to the system."
>>>
>>> But a truck has many causes external to the system. According to Odds
>>> Bodkin in the previous message, "There are
>>> indeed at least four forces acting on the car (air resistance pushing
>>> backwards, the friction between the tires and the road surface pushing the
>>> car forward — that’s where the engine comes in, the force of gravity
>>> downwards, and the force of the road pushing upward),"
>> Yes, but it is still true in an inertial system that all the forces sum to
>> zero, no matter how you count them up, to the precision relevant to the
>> analysis. I listed the non transient and large ones. Wind gusts are not of
>> that category.
>
> Newton's first law of motion is: "An object at rest remains at rest, and an
> object in motion remains in motion at constant speed and in a straight line
> unless acted on by an unbalanced force."
>
> An "inertial system" is defined as "a frame of reference in which a body
> remains at rest or moves with constant linear velocity unless acted upon
> by forces."

Unless acted on by a NET force.

Note that an inertial system is then a frame of reference in which Newton’s
first law holds.

>
> Since we are talking about a truck moving on the curved surface of the
> earth, that definition of "inertial system" does not apply.

Again, I said a FLAT road, not one that follows the curvature of the earth.
But in any event, the curvature of the earth is a small effect over the
course of a minute or so that the car is being tracked. The drop over a
mile is 8”. For the purposes of modeling, this is close enough to being
inertial, depending on the precision needed.

>
> The idea that a moving truck can be an "inertial system" is just IDIOTIC
> to me.

Yes, I know, because you are using a different definition of “inertial
motion” than what it really means.
First of all, you don’t seem to understand how a NET force can be zero or
even close to zero if there are four big forces present. To you, inertial
motion means “no forces present at all, even tiny ones”. That’s not a
correct understanding of that term.

This is FIRST YEAR physics. The problem you have is not with relativity at
all. It has to do with basic, week 1, first year physics, and whether you
buy into these basic things.

> FORCE makes the truck move. It is the driver's foot that causes
> FORCE to be applied to the truck to cause it to move at APPROXIMATELY
> 50 mph. There is "NO BALANCE OF FORCES," there is just STEADY FORCE.
>
> We seem to have irreconcilable differences. So, there is no point in
> continuing on any discussion about inertia.
>
> So, I'm done here --- unless someone addresses the FACT that light will
> hit a moving observer at c+v or c-v.
>
> Ed
>

--
Odd Bodkin -- maker of fine toys, tools, tables

On Tuesday, November 16, 2021 at 11:37:42 AM UTC-6, rotchm wrote:
> On Tuesday, November 16, 2021 at 12:21:48 PM UTC-5, wrote:
>
>
> > An "inertial system" is defined as "a frame of reference in which a body
> > remains at rest or moves with constant linear velocity unless acted upon
> > by forces."
> >
> > Since we are talking about a truck moving on the curved surface of the
> > earth, that definition of "inertial system" does not apply.
> Yes it does apply. Again, we are discussing inertial system (inertial motion) to within the *confines of the discussion*, the *setup*, to within our desired accuracies. When we say that the truck is coasting at 50mph, we mean that all the little vibrations, shape of the earth, etc are too small and insignificant for *our* purposes. We all have been telling you this. Do you realize it now?
>
> So now, do you agree that a truck coasting at 50 mph is an inertial system?
> > We seem to have irreconcilable differences. So, there is no point in
> > continuing on any discussion about inertia.
> We are not discussing inertia. We are discussing inertial systems, inertial motion. We must continue to discuss this, the meaning of the words, before we discuss further.
> > So, I'm done here ---
> No you are not. You agreed to discuss first the meaning of the words. We have not resolved that yet. So we must continue. Do not coward away. Be honest and finish the discussion you proposed. Recall you proposed discussing only one topic. And the topic we have been discussing is the meaning of the words used. In particular, inertial system.

Arguing here won't resolve anything. You all just recite what you were
evidently taught in school. Somehow you believe that a moving truck
is an inertial system, even though definitions of inertial systems say
that the system will move FOREVER unless some external force is applied.
With a truck, forces are applied constantly to keep it moving. FUEL IS
EXPENDED. If those forces are removed, the truck will come to a stop.
In NO WAY is a moving truck an inertial system.

So, I'm going to do some research to see if I can find ANY physics book
that suggests that a powered truck is an "inertial system."

The first book I checked was “Fundamentals of College Physics” by Peter J. Nolan,
section 4-2 which says:

"Newton’s first law of motion also defines what is called an inertial coordinate system. A coordinate system
in which objects experiencing no unbalanced forces remain at rest or continue in uniform motion, is called an
inertial coordinate system. An inertial coordinate system (also called an inertial reference system) is a
coordinate system that is either at rest or moving at a constant velocity with respect to another coordinate system
that is either at rest or also moving at a constant velocity. In such a coordinate system the first law of motion holds."

"In this book nearly all coordinate
systems will be either inertial coordinate systems or ones that can be approximated by inertial coordinate systems,
hence Newton’s first law will be valid. The earth is technically not an inertial coordinate system because of its
rotation about its axis and its revolution about the sun. The acceleration caused by the rotation about its axis is
only about 1/300 of the acceleration caused by gravity, whereas the acceleration due to its orbital revolution is
about 1/1650 of the acceleration due to gravity. Hence, as a first approximation, the earth can usually be used as
an inertial coordinate system."

It doesn't help much, but it says "as a first approximation, the earth can usually be used as
an inertial coordinate system."

Ed

El martes, 16 de noviembre de 2021 a las 15:10:47 UTC-3, det...@outlook.com escribió:
> On Tuesday, November 16, 2021 at 11:37:42 AM UTC-6, rotchm wrote:

> > No you are not. You agreed to discuss first the meaning of the words. We have not resolved that yet. So we must continue. Do not coward away. Be honest and finish the discussion you proposed. Recall you proposed discussing only one topic. And the topic we have been discussing is the meaning of the words used. In particular, inertial system.
> Arguing here won't resolve anything. You all just recite what you were
> evidently taught in school. Somehow you believe that a moving truck
> is an inertial system, even though definitions of inertial systems say
> that the system will move FOREVER unless some external force is applied.
> With a truck, forces are applied constantly to keep it moving. FUEL IS
> EXPENDED. If those forces are removed, the truck will come to a stop.
> In NO WAY is a moving truck an inertial system.
>
> So, I'm going to do some research to see if I can find ANY physics book
> that suggests that a powered truck is an "inertial system."
>
> The first book I checked was “Fundamentals of College Physics” by Peter J. Nolan,
> section 4-2 which says:
>
> "Newton’s first law of motion also defines what is called an inertial coordinate system. A coordinate system
> in which objects experiencing no unbalanced forces remain at rest or continue in uniform motion, is called an
> inertial coordinate system. An inertial coordinate system (also called an inertial reference system) is a
> coordinate system that is either at rest or moving at a constant velocity with respect to another coordinate system
> that is either at rest or also moving at a constant velocity. In such a coordinate system the first law of motion holds."
>
> "In this book nearly all coordinate
> systems will be either inertial coordinate systems or ones that can be approximated by inertial coordinate systems,
> hence Newton’s first law will be valid. The earth is technically not an inertial coordinate system because of its
> rotation about its axis and its revolution about the sun. The acceleration caused by the rotation about its axis is
> only about 1/300 of the acceleration caused by gravity, whereas the acceleration due to its orbital revolution is
> about 1/1650 of the acceleration due to gravity. Hence, as a first approximation, the earth can usually be used as
> an inertial coordinate system."
>
> It doesn't help much, but it says "as a first approximation, the earth can usually be used as
> an inertial coordinate system."
>
> Ed

http://www.phys.unsw.edu.au/einsteinlight/jw/module1_Inertial.htm

"Inertial frames
Newton's laws work — sometimes. At other times, they appear not to work. Frames of reference in which Newton's laws of motion are observed are called Inertial Frames. For instance, the surface of the Earth is almost* an inertial frame. When we analyse the behaviour of objects with respect to the Earth, we nearly* always find that F = ma. Further, in the particular case where F = 0, objects maintain constant velocity.

* The 'almost' and 'nearly' are inserted above because of the Earth's own accelerated motion. (Travel in a straight line would make no difference, but rotation and orbital motion involve accelerations.) The daily rotation is quite slow: only one turn per day is 0.004 degree per second: this is why we cannot feel it. However, if we could observe motion over many minutes, we should notice that, for an object subject to negligible external forces, measurements made with respect to the laboratory frame show a very small acceleration. This acceleration is best considered as the acceleration of the laboratory with respect to the object: the result of the rotation of the laboratory, which turns with the Earth. The Earth is approximately, but not quite, an inertial frame. See the Foucault pendulum and coriolis forces for a more detailed discussion of this point."

" Non inertial frames. In measurements made with respect to some other frames of reference, Newton's laws appear to be violated. For example, when the bus goes round a corner, a standing passenger who is not holding on seems to find himself accelerating sideways. If you try throwing and catching balls on a merry-go-round, you'll also observe some apparent violations of Newton's laws. Try this animation:

Zoe throws a ball from the centre of the a merry-go-round. To Zoe, turning clockwise with the merry-go-round (picture at left), the ball seems to curve to the left - it travels anti-clockwise. To an observer who is not rotating (e.g. someone in a tree above, picture at right, or to Jasper, sitting on the ground), the merry-go-round turns clockwise and the ball travels in a vertical plane (and thus a straight line, seen from above).

If you forget the outside world and refer everything to the frame of the merry-go-round, then you need to invent other fictitious forces which make moving objects turn. Newton's laws work in systems that are not spinning with respect to the distant galaxies. In frames of reference which spin, the 'extra forces' that have to be invoked to retain Newton's laws are fictitious forces called centrifugal forces and Coriolis forces.

For a ball thrown on the surface of the earth, the earth hardly rotates during its flight (say 0.01 degree) so we do not notice the Coriolis force. For the sustained swinging of the Foucault pendulum, we could say that the Coriolis force makes it veer slightly to the left, and precess slowly anti-clockwise. Also in the Southern hemisphere, ocean currents and winds similarly tend to veer to the left: major circulations such as the South Pacific Current are anti-clockwise due to these Coriolis forces.

Centrifugal forces are an example of imaginary forces invented to explain motion in a non-inertial frame.

Why doesn't this man fall off his bicycle? An external observer would say that he is turning and therefore accelerating to the right (his left). If he could forget that he is in a non-inertial frame he might say that there is a mysterious 'centrifugal force' pushing him outwards, and he is leaning in against the 'force'. If he sat upright on the bicycle while turning, the 'centrifugal force' would seem to push him over sideways.

If he closes his eyes, can he tell whether he is upright and travelling straight, or turning and leaning inwards on the corner? A negative answer to this question (or usually a more simple version involving linear acceleration) is the starting point for the General Theory of Relativity, which is Einstein's theory of gravitation and accelerated motion. But we're getting ahead of ourselves here! "

On Tuesday, November 16, 2021 at 1:10:47 PM UTC-5, det...@outlook.com wrote:

> Arguing here won't resolve anything.

So why do you continuously come here and argue?

> You all just recite what you were evidently taught in school.

If we are to discuss, we need to know the meaning of the words we use, agree?

> Somehow you believe that a moving truck
> is an inertial system, even though definitions of inertial systems say
> that the system will move FOREVER unless some external force is applied.

Know the definition does not say that at all. Stop making things up. Can you state a definition of it here? I gave you one, can you give one? Or do we agree on the same definition?

In the definition, interior or exterior forces are irrelevant. As long as the system is not accelerating, it's an inertial system. There may be forces or there may be no forces. If the ***net*** force is zero, then the system is not accelerating. It is therefore an inertial system.

> With a truck, forces are applied constantly to keep it moving. FUEL IS
> EXPENDED.

And irrelevant to the definition. As long as the system is moving at constant speed, not accelerating, it is an inertial system. Do you agree that the definition says. And only that?

> If those forces are removed, the truck will come to a stop.

No it won't, if you remove all forces from it, the net force is zero hence acceleration 0.
Don't forget in your example if you say if you remove the forces hands you are removing also all frictions with the ground and air, then there is no more forces.

> In NO WAY is a moving truck an inertial system.

But according to the definition, it is. As long that it is not accelerating, it's an inertial system. That is what the definition says.

"an inertial frame of reference is a frame of reference that is not undergoing acceleration.".

Hear about is the definition. Do you accept this definition? Is there something you do not understand in it?
Is your truck example undergoing acceleration? What is its accelerometer indicating?

> So, I'm going to do some research to see if I can find ANY physics book
> that suggests that a powered truck is an "inertial system."

OK

> The first book I checked was “Fundamentals of College Physics” by Peter J. Nolan,
> section 4-2 which says:
>
> "Newton’s first law of motion also defines what is called an inertial coordinate system. A coordinate system
> in which objects experiencing no unbalanced forces remain at rest or continue in uniform motion, is called an
> inertial coordinate system.

Yes, that is equivalent to an inertial system. Note here that "no unbalanced forces" means net force of zero.
Another way to view an ibertial system is that if you put a ball somewhere and let it go it stays there. If this is true at every point in your system, then their system is an inertial frame.

> "In this book nearly all coordinate
> systems will be either inertial coordinate systems or ones that can be approximated by inertial coordinate systems,
> hence Newton’s first law will be valid. The earth is technically not an inertial coordinate system because of its
> rotation about its axis and its revolution about the sun. The acceleration caused by the rotation about its axis is
> only about 1/300 of the acceleration caused by gravity, whereas the acceleration due to its orbital revolution is
> about 1/1650 of the acceleration due to gravity. Hence, as a first approximation, the earth can usually be used as
> an inertial coordinate system."

Correct, as we have been telling you. No need to repeat it.

> It doesn't help much, but it says "as a first approximation, the earth can usually be used as
> an inertial coordinate system."

Yes, as we have been telling you. It is inertial to within our desired accuracies.
Even your truck if it's stopped on the ground, it is not an inertial system.. But for our purposes, for the accuracies of our systems, it is inertial.
This is why in physics we have operational definitions. This takes account the actresses of the devices.

Paparios wrote:

>> Ed
>
> http://www.phys.unsw.edu.au/einsteinlight/jw/module1_Inertial.htm
>
> "Inertial frames Newton's laws work — sometimes. At other times, they
> appear not to work. Frames of reference in which Newton's laws of motion

nothing to do with newton, it's a fact.

Ed Lake <detect@outlook.com> wrote:
> On Tuesday, November 16, 2021 at 11:37:42 AM UTC-6, rotchm wrote:
>> On Tuesday, November 16, 2021 at 12:21:48 PM UTC-5, wrote:
>>
>>
>>> An "inertial system" is defined as "a frame of reference in which a body
>>> remains at rest or moves with constant linear velocity unless acted upon
>>> by forces."
>>>
>>> Since we are talking about a truck moving on the curved surface of the
>>> earth, that definition of "inertial system" does not apply.
>> Yes it does apply. Again, we are discussing inertial system (inertial
>> motion) to within the *confines of the discussion*, the *setup*, to
>> within our desired accuracies. When we say that the truck is coasting at
>> 50mph, we mean that all the little vibrations, shape of the earth, etc
>> are too small and insignificant for *our* purposes. We all have been
>> telling you this. Do you realize it now?
>>
>> So now, do you agree that a truck coasting at 50 mph is an inertial system?
>>> We seem to have irreconcilable differences. So, there is no point in
>>> continuing on any discussion about inertia.
>> We are not discussing inertia. We are discussing inertial systems,
>> inertial motion. We must continue to discuss this, the meaning of the
>> words, before we discuss further.
>>> So, I'm done here ---
>> No you are not. You agreed to discuss first the meaning of the words. We
>> have not resolved that yet. So we must continue. Do not coward away. Be
>> honest and finish the discussion you proposed. Recall you proposed
>> discussing only one topic. And the topic we have been discussing is the
>> meaning of the words used. In particular, inertial system.
>
> Arguing here won't resolve anything. You all just recite what you were
> evidently taught in school. Somehow you believe that a moving truck
> is an inertial system, even though definitions of inertial systems say
> that the system will move FOREVER unless some external force is applied.

Until some external NET force is applied. I gather you don’t know what “net
force” means.

If you put the car in neutral, disengaging the engine, there is now a NET
force on the car, caused by air resistance. While the engine was running
and engaged, there was no NET force on the car.

If this is obscure to you, it’s because you’ve never learned to diagram
forces on an object and how to sum them up. This is a first-year,
first-month physics exercise. This is why it’s useful to READ introductory
physics books and to work the problems.

> With a truck, forces are applied constantly to keep it moving. FUEL IS
> EXPENDED. If those forces are removed, the truck will come to a stop.
> In NO WAY is a moving truck an inertial system.
>
> So, I'm going to do some research to see if I can find ANY physics book
> that suggests that a powered truck is an "inertial system."

Sure, go for it.

>
> The first book I checked was “Fundamentals of College Physics” by Peter J. Nolan,
> section 4-2 which says:
>
> "Newton’s first law of motion also defines what is called an inertial
> coordinate system. A coordinate system
> in which objects experiencing no unbalanced forces remain at rest or
> continue in uniform motion, is called an
> inertial coordinate system. An inertial coordinate system (also called an
> inertial reference system) is a
> coordinate system that is either at rest or moving at a constant velocity
> with respect to another coordinate system
> that is either at rest or also moving at a constant velocity. In such a
> coordinate system the first law of motion holds."
>
> "In this book nearly all coordinate
> systems will be either inertial coordinate systems or ones that can be
> approximated by inertial coordinate systems,
> hence Newton’s first law will be valid. The earth is technically not an
> inertial coordinate system because of its
> rotation about its axis and its revolution about the sun. The
> acceleration caused by the rotation about its axis is
> only about 1/300 of the acceleration caused by gravity, whereas the
> acceleration due to its orbital revolution is
> about 1/1650 of the acceleration due to gravity. Hence, as a first
> approximation, the earth can usually be used as
> an inertial coordinate system."
>
> It doesn't help much, but it says "as a first approximation, the earth
> can usually be used as
> an inertial coordinate system."

Yes, which is what I told you, and which you didn’t believe, and so I
suggested you look in a book, which you’ve done now. Congratulations.

At least now you’re starting to read early chapters of first year books,
which is what you should have done years ago.

>
> Ed
>

--
Odd Bodkin -- maker of fine toys, tools, tables

On 11/16/2021 12:16 PM, Michael Moroney wrote:
> On 11/16/2021 11:50 AM, Ed Lake wrote:
>> On Tuesday, November 16, 2021 at 9:55:26 AM UTC-6, Paparios wrote:

>> Yes, studying would help me figure out where you get your screwball
>> ideas.
>
> Newton and Galileo.
>
> That are the DEFINITION of inertial frames.

"That IS the DEFINITION..."

>  You can't make up your own
> definition and say the actual definition is wrong according to YOUR
> definition.

>> Another issue is what would that cop measure if he was INSIDE the truck?
>> Answer:  He would measure a speed of zero.  Why?
>
> Because the returned signal is the same frequency as the transmitted
> signal because the gun and truck wall are all stationary in a certain
> frame of reference.
>
>>  Because his radar gun
>> would emit photons at c that hit the real wall of the truck at c+v,
>
> Ignoring the second postulate violation, why would the frame used jump
> to the road frame here?

I got this backwards. The questions asked really should be "Why are you
using the road frame for the radar gun when the radar gun is in the
truck and moving with the truck", then "Why did you switch to the truck
frame when the beam strikes the wall?"
>
>> then atoms
>> in the wall emit photons back to the gun at c that hit the gun at c-v.
>
> And why did you switch back to the truck frame again?

Should be "Why did you switch back to the road frame when the radar gun
is in the truck and moving with it?"
>
>>  The
>> gun then computes c+v-v=c
>
> Nope, because of time of travel, "c+v-c" really is sqrt(c^2-v^2), always
> less than c.
>
>>  and gets a speed of zero .
>
> Nope.
>>
>> My proposed experiment would eliminate one of those two measurements.
>> If you have TWO radar guns with IDENTICAL frequencies pointed at each
>> other, each gun would emit photons at c that hit the other gun at either
>> c+v or c-v.
>
> How are the guns moving? Apparently one at v relative to the other?
>
>>  Each gun would receive the photons from the other gun as if
>> they were returning from a target.  Radar guns show the fastest measured
>> speed, so, instead of showing zero, one gun will show +50 mph and the
>> other gun will show -50 mph.
>
> The only way this would happen is if one gun was alongside the road and
> the other gun was moving in the truck, aimed through the windshield or
> something.
>>
>> You all claim this is impossible, because the truck is an  inertial
>> system."
>> I say it is a "propelled system."
>
> It IS an inertial system, by the definition of an inertial system.
>
>> I cannot call it an "accelerating" system
>> because the word "accelerate" means "to cause to increase speed."
>
> You got something correct for once.
> Since it is not an accelerating system, it is an inertial system.
>
>>  In
>> reality, the truck is constantly accelerating and decelerating in
>> order to
>> maintain a steady speed.
>
> Your nitpicks are a sign of desperation, as I already said.
>>
>> The only way I see out of this dilemma
>
> No dilemma, except in your mind.
>
>> is for people here to understand
>> that photons EMITTED at c hit a moving OBSERVER at c+v or c-v where
>> v is the speed of the observer toward or away from the emitter.
>
> Why do you think people should disregard the second postulate?
>
>
>>  That is
>> what MANY EXPERIMENTS show.
>
> No experiments show that.
>
>>  I list and describe those experiments
>> here: www.ed-lake.com/Speed-of-received-light.html
>
> All full of the same errors I already pointed out.
>
> You couldn't pass high school physics with those mistakes.

On Tuesday, November 16, 2021 at 9:21:48 AM UTC-8, det...@outlook.com wrote:

> So, I'm done here...

It's about time, Ed, you have been done here for a very long time now...

> ... --- unless someone addresses the FACT that light will hit a moving observer at c+v or c-v.

Well, that is not likely to happen unless one of your fellow crackpots joins in and agrees with you. You obviously don't know what you don't know, and your personal ignorance of relativity is vast indeed!

On Tuesday, 16 November 2021 at 16:55:26 UTC+1, Paparios wrote:
> El martes, 16 de noviembre de 2021 a las 12:41:12 UTC-3, det...@outlook.com escribió:
> > On Monday, November 15, 2021 at 3:24:59 PM UTC-6, bodk...@gmail.com wrote:
>
> > > You, however, have decided in your infinite wisdom that inertial motion
> > > must mean something like “at rest relative to the nearest unpropelled
> > > massive body, such as the earth’s surface”. It doesn’t mean anything like
> > > that at all. It means what I said it means above, which you can actually
> > > check for yourself by READING a freshman physics text, rather than just
> > > trying to sort this all out in your own head.
>
> > Okay. Very interesting. So, when a truck is being propelled at a constant
> > 80 mph down I-94, it is an inertial system. You realize, of course, that the
> > truck is bumping over cracks in the pavement, it is being pushed by winds, the
> > truck driver's foot on the gas pedal is not perfectly steady, so the speed
> > actually varies a bit up and down. And yet you believe it is an inertial
> > system.
> >
> > And a police officer, who is standing on A DIFFERENT inertial system,
> > the earth, can point a radar gun at the truck and measure the truck's speed.
> >
> > I'd say that your BELIEF as to what constitutes an "inertial system" is
> > just that, your BELIEF. It doesn't have anything to do with reality.
> >
> > Ed
> It is not a belief. It is what physicists have defined as inertial systems:
>
> "In classical physics and special relativity

Poor Paparios trash diplomatically didn't mention general relativity,
where his fellow idiots have defined inertial systems very differently.

On Tuesday, 16 November 2021 at 18:16:05 UTC+1, Michael Moroney wrote:
> On 11/16/2021 11:50 AM, Ed Lake wrote:
> > On Tuesday, November 16, 2021 at 9:55:26 AM UTC-6, Paparios wrote:
> >> El martes, 16 de noviembre de 2021 a las 12:41:12 UTC-3, escribió:
> >>> On Monday, November 15, 2021 at 3:24:59 PM UTC-6, bodk...@gmail.com wrote:
> >>
> >>>> You, however, have decided in your infinite wisdom that inertial motion
> >>>> must mean something like “at rest relative to the nearest unpropelled
> >>>> massive body, such as the earth’s surface”. It doesn’t mean anything like
> >>>> that at all. It means what I said it means above, which you can actually
> >>>> check for yourself by READING a freshman physics text, rather than just
> >>>> trying to sort this all out in your own head.
> >>
> >>> Okay. Very interesting. So, when a truck is being propelled at a constant
> >>> 80 mph down I-94, it is an inertial system. You realize, of course, that the
> >>> truck is bumping over cracks in the pavement, it is being pushed by winds, the
> >>> truck driver's foot on the gas pedal is not perfectly steady, so the speed
> >>> actually varies a bit up and down. And yet you believe it is an inertial
> >>> system.
> >>>
> >>> And a police officer, who is standing on A DIFFERENT inertial system,
> >>> the earth, can point a radar gun at the truck and measure the truck's speed.
> >>>
> >>> I'd say that your BELIEF as to what constitutes an "inertial system" is
> >>> just that, your BELIEF. It doesn't have anything to do with reality.
> >>>
> >>> Ed
> >> It is not a belief. It is what physicists have defined as inertial systems:
> >>
> >> "In classical physics and special relativity, an inertial frame of reference is a frame of reference that is not undergoing acceleration. In an inertial frame of reference, a physical object with zero net force acting on it moves with a constant velocity (which might be zero)—or, equivalently, it is a frame of reference in which Newton's first law of motion holds. An inertial frame of reference can be defined in analytical terms as a frame of reference that describes time and space homogeneously, isotropically, and in a time-independent manner. Conceptually, the physics of a system in an inertial frame have no causes external to the system. An inertial frame of reference may also be called an inertial reference frame, inertial frame, Galilean reference frame, or inertial space.
> >>
> >> All inertial frames are in a state of constant, rectilinear motion with respect to one another; an accelerometer moving with any of them would detect zero acceleration. Measurements in one inertial frame can be converted to measurements in another by a simple transformation (the Galilean transformation in Newtonian physics and the Lorentz transformation in special relativity). In general relativity, in any region small enough for the curvature of spacetime and tidal forces to be negligible, one can find a set of inertial frames that approximately describe that region".
> >>
> >> You need to study a lot more!!!!
> >
> > Yes, studying would help me figure out where you get your screwball
> > ideas.
> Newton and Galileo.
>
> That are the DEFINITION of inertial frames.

Poor idiot Einstein has refuted these common sense prejudices,
however. Have you ever heard of his famous elevator gedanken,
stupid Mike?

On 11/16/2021 12:21 PM, Ed Lake wrote:

> Newton's first law of motion is: "An object at rest remains at rest, and an
> object in motion remains in motion at constant speed and in a straight line
> unless acted on by an unbalanced force."

Yes, like the truck. Remember, friction/air resistance is a force on it.
>
> An "inertial system" is defined as "a frame of reference in which a body
> remains at rest or moves with constant linear velocity unless acted upon
> by forces."

Unbalanced forces. Now, the same as above, Newton's First Law.
>
> Since we are talking about a truck moving on the curved surface of the
> earth, that definition of "inertial system" does not apply.

The idea is that such differences are small enough so that they don't
matter.
>
> The idea that a moving truck can be an "inertial system" is just IDIOTIC
> to me.

It doesn't matter what you think. The definition of "inertial system"
is one where there is no net force, one where there is no acceleration.

> FORCE makes the truck move. It is the driver's foot that causes
> FORCE to be applied to the truck to cause it to move at APPROXIMATELY
> 50 mph. There is "NO BALANCE OF FORCES," there is just STEADY FORCE.

If the forces are unbalanced, then there is an acceleration. It was
stated from the very beginning the truck is moving at a CONSTANT 50 mph
so it is NOT accelerating. Your homework assignment is to find which of
Newton's Laws discusses forces/acceleration.
>
> We seem to have irreconcilable differences. So, there is no point in
> continuing on any discussion about inertia.

The "irreconcilable differences" are simply your idée fixe, which blocks
your understanding of simple high school physics. As long as you remain
stubborn and refer to your BELIEFS as FACTS, and make up your own
definitions for things like "inertial frame", you'll remain as a
stubborn ignoramus of physics.
>
> So, I'm done here --- unless someone addresses the FACT that light will
> hit a moving observer at c+v or c-v.

Speaking of you calling your BELIEFS as FACTS...

On 11/16/2021 1:10 PM, Ed Lake wrote:
> On Tuesday, November 16, 2021 at 11:37:42 AM UTC-6, rotchm wrote:
>> On Tuesday, November 16, 2021 at 12:21:48 PM UTC-5, wrote:
>>
>>
>>> An "inertial system" is defined as "a frame of reference in which a body
>>> remains at rest or moves with constant linear velocity unless acted upon
>>> by forces."
>>>
>>> Since we are talking about a truck moving on the curved surface of the
>>> earth, that definition of "inertial system" does not apply.
>> Yes it does apply. Again, we are discussing inertial system (inertial motion) to within the *confines of the discussion*, the *setup*, to within our desired accuracies. When we say that the truck is coasting at 50mph, we mean that all the little vibrations, shape of the earth, etc are too small and insignificant for *our* purposes. We all have been telling you this. Do you realize it now?
>>
>> So now, do you agree that a truck coasting at 50 mph is an inertial system?
>>> We seem to have irreconcilable differences. So, there is no point in
>>> continuing on any discussion about inertia.
>> We are not discussing inertia. We are discussing inertial systems, inertial motion. We must continue to discuss this, the meaning of the words, before we discuss further.
>>> So, I'm done here ---
>> No you are not. You agreed to discuss first the meaning of the words. We have not resolved that yet. So we must continue. Do not coward away. Be honest and finish the discussion you proposed. Recall you proposed discussing only one topic. And the topic we have been discussing is the meaning of the words used. In particular, inertial system.
>
> Arguing here won't resolve anything. You all just recite what you were
> evidently taught in school.

And you just recite what your idée fixe makes you recite. It controls you.

> Somehow you believe that a moving truck
> is an inertial system, even though definitions of inertial systems say
> that the system will move FOREVER unless some external force is applied.

Which is correct, it would move forever without a NET external force.
For a truck, there is ALWAYS air resistance and friction as long as it
is moving relative to the air/road.

> With a truck, forces are applied constantly to keep it moving. FUEL IS
> EXPENDED. If those forces are removed, the truck will come to a stop.

Because the air resistance/frictional force is no longer balanced, and
it always opposes the motions, so the truck decelerates.

> In NO WAY is a moving truck an inertial system.

Since it is not accelerating, it is an inertial system by definition.
>
> So, I'm going to do some research to see if I can find ANY physics book
> that suggests that a powered truck is an "inertial system."
>
> The first book I checked was “Fundamentals of College Physics” by Peter J. Nolan,
> section 4-2 which says:
>
> "Newton’s first law of motion also defines what is called an inertial coordinate system. A coordinate system
> in which objects experiencing no unbalanced forces remain at rest or continue in uniform motion, is called an
> inertial coordinate system. An inertial coordinate system (also called an inertial reference system) is a
> coordinate system that is either at rest or moving at a constant velocity with respect to another coordinate system
> that is either at rest or also moving at a constant velocity. In such a coordinate system the first law of motion holds."
>
> "In this book nearly all coordinate
> systems will be either inertial coordinate systems or ones that can be approximated by inertial coordinate systems,
> hence Newton’s first law will be valid. The earth is technically not an inertial coordinate system because of its
> rotation about its axis and its revolution about the sun. The acceleration caused by the rotation about its axis is
> only about 1/300 of the acceleration caused by gravity, whereas the acceleration due to its orbital revolution is
> about 1/1650 of the acceleration due to gravity. Hence, as a first approximation, the earth can usually be used as
> an inertial coordinate system."
>
> It doesn't help much,

It should.

> but it says "as a first approximation, the earth can usually be used as
> an inertial coordinate system."

As can the truck.