[ZX-E]

Originally Posted by IamIan

I will agree I am far from perfect and do not always word things perfectly.

Given the responses ( not just from major ) , I doubt it would have mattered how it was phrased... as I said from the beginning it was an academic point... and I shouldn't have even brought it up... In the future I'll try and bite my virtual tongue instead.

but ... as I also said from the beginning ... it doesn't matter.

Do I now move on to the other incorrect statements, and misinterpretations .... no ... it does not look to be worth the hassle... each time I've tried to explain one thing it has lead to other misinterpretations .... and it only looks to be building momentum and branching out to more and more things... that just isn't appealing to me... maybe some other time in a different format... But I am just not feeling that argumentative right now.

Well I'm sorry you feel that way. Please don't bite your virtual tongue.

To be honest I really do think it would have mattered how it was phrased. You were saying that even if the motor's shaft isn't turning there can be power dissipated by the motor in the form of thermal energy. Right? Everyone can agree on that I think .

[IamIan]

Originally Posted by ZX-E

To be honest I really do think it would have mattered how it was phrased. You were saying that even if the motor's shaft isn't turning there can be power dissipated by the motor in the form of thermal energy. Right? Everyone can agree on that I think .

Although I had hoped others would have seen it without been spoon feed.

But, yes that one should be obvious... but it isn't just thermal power from the flow of and conversion to and from thermal energy... there are many many type of power and many many types of energy ... many many of which are still present at an electric motor at 0 RPMs... but not in a stationary spring.

Additionally ... it is often over looked that kinetic power is not the same as mechanical power .... kinetic power could be power from any type of movement.... mechanical power ignores any movement that is perpendicular to the applied force.

A crude example... yes it is flawed but I don't know off hand a better analogy...

A bolt and a nut ... you apply a force to turn the bolt ... the movement of the bolt in the direction of that applied force of rotation counts toward that mechanical power ... but the motion of the bolt toward or away from the nut does not count for that mechanical power because it is a motion that is perpendicular to the applied force.... Yes I can hear the masses screaming already... but its true... if you don't think so go look up mechanical power... Now the best you could do is that you could do with mechanical power is change your frame of reference ... the force and movement toward or away from the bolt is induced and in that frame of reference the rotational force and movement are ignored because they are now perpendicular.

In short... invoking mechanical power ignores allot of things ... to many for my tastes... and still does not change the presence of power at 0 RPMs.

Originally Posted by ZX-E

Well I'm sorry you feel that way. Please don't bite your virtual tongue.

but it has treed out so much...

If this one rather simple concept was such a fight where am I for

Duncan and his post with by my count... 4 points I disagree with.
Major and his most recent post by my count ... 5 points I disagree with.

or any of the older multitudes of points I disagree with.

I just see an steep uphill battle ... with very very little to be gained by the effort... and a very good chance they will never see it no matter what.

[major]

Originally Posted by IamIan

A bolt and a nut ... you apply a force to turn the bolt ... the movement of the bolt in the direction of that applied force of rotation counts toward that mechanical power ... but the motion of the bolt toward or away from the nut does not count for that mechanical power because it is a motion that is perpendicular to the applied force.... Yes I can hear the masses screaming already... but its true... if you don't think so go look up mechanical power... Now the best you could do is that you could do with mechanical power is change your frame of reference ... the force and movement toward or away from the bolt is induced and in that frame of reference the rotational force and movement are ignored because they are now perpendicular.

Hi Iam,

Me again. Yeah, a bolt and nut. Good example. We all use those. And some of us use a torque wrench. When tightening a bolt and nut, what are you doing? Drawing the nut to the bolt head squeezing the material between the two. So there is a force parallel to the axis of rotation of the bolt and torque wrench. This force is translated into torque by the bolt thread radius and the thread pitch. So the force squeezing the material between the nut and bolt head (and the work done to move the nut or bolt, and the power associated with that work) is translated to the torque on the wrench (and the work done and associated power on the wrench).

This is much the same as the rotation to translational mechanical power transformation which occurs in the EV via the wheel. Torque is applied to the axle and translated to linear force via the wheel radius.

We all know this. The linear motion, force, work, and power is considered and accounted for in the rotational coordinate system, namely the motor output torque.

What is your point? No force, power or energy is ignored, unless it is so insignificant it cannot be measured by reasonable means, meaning 10^-12%.

Regards,

major

[IamIan]

Originally Posted by major

What is your point? No force, power or energy is ignored, unless it is so insignificant it cannot be measured by reasonable means, meaning 10^-12%.

....
Although I am 90% certain this effort I am about to make will still not be understood if it wasn't already... for the hell of it I'll give it a try.
....

In regards to my point on invoking mechanical power.

By invoking mechanical power you ignore all motion perpendicular to the applied force... that is just how mechanical power works and is calculated ... look it up... look at the Formulas and think about it.

I am not saying there isn't movement... I am not saying there isn't power... I am not saying the power was not converted from rotation force... I am not saying there is not a corresponding counter force or drag on the applied force that relates to the induced perpendicular force... I am not suggesting magic... I am not suggesting the perpendicular force comes from no where... I am not suggesting the perpendicular force does not originate from the applied force... I am not saying the perpendicular power can't be accounted for.

I'm sure I missed several other things I am also not saying.

I'm sure someone will focus on something I'm not saying either by one I missed in the list or by ignoring what I am saying.

Also I will repeat what I said from the beginning... I think this is at least 90% academic... if not 99%.

--------------------

There are two frames of reference.

The rotational frame of reference :
Apply a force in a rotational direction ... if that force causes movement in the rotational direction + or - movement mechanical power is present and + or - work is done in that frame of reference.

The perpendicular frame of reference:
Any motion that occurs perpendicular to the applied force... it is no accident that there is no term for this in RPM & torque power Formulas ... mechanical power ignores any motion perpendicular to the applied force.

We can go back to what I am not saying if you like... or just page up.

If a motion occurred perpendicular to the axis of rotation the force of that motion still comes from the energy applied to the system... this motion might be experienced as a vibration, or sound, etc...

A motor with energy flow has power ( several different kinds ) even while held stationary... If it is only stationary in the rotational frame of reference but is not stationary in the perpendicular frame of reference ... there is still no rotational frame of reference mechanical power no matter how much it moves in the perpendicular frame of reference... There is mechanical power in the perpendicular frame of reference while it moves in that direction but it is ignored in the rotational frame of reference ... If the motor is allowed to rotate any rotational movement is ignored and does not count as mechanical power in the perpendicular frame of reference.

In addition to all the other forms of power that are ignored when mechanical power is invoked ... you also ignore several types of physical movement as well depending on your chosen frame of reference that mechanical power conventions require you to pick one frame of reference.

-----------------

The several other points from older posts I will not even attempt to go into in this post... which is already long enough even after condensing it.

[major]

Originally Posted by IamIan

....Any motion that occurs perpendicular to the applied force... it is no accident that there is no term for this in RPM & torque power formulas ... mechanical power ignores any motion perpendicular to the applied force.

But there is a term. Radius. T = r x F This is a vector formula. See http://en.wikipedia.org/wiki/Torque

Through the radius, and inclined plane, all translational quantities are accounted for in the rotational system.

If your "perpendicular motion" is a result of the motor, then it is accounted for in the torque and angular velocity of the output shaft.

Now if that perpendicular motion is a result of driving off a cliff, I guess I have ignored that back at the motor shaft

Regards,

major

[IamIan]

Originally Posted by IamIan

....
Although I am 90% certain this effort I am about to make will still not be understood if it wasn't already... for the hell of it I'll give it a try.
....

In regards to my point on invoking mechanical power.

By invoking mechanical power you ignore all motion perpendicular to the applied force... that is just how mechanical power works and is calculated ... look it up... look at the formulas and think about it.

I called it... maybe next time I should put money down to...

Originally Posted by major

But there is a term. Radius. T = r x F This is a vector formula. See http://en.wikipedia.org/wiki/Torque

Through the radius, and inclined plane, all translational quantities are accounted for in the rotational system.

If your "perpendicular motion" is a result of the motor, then it is accounted for in the torque and angular velocity of the output shaft.

Now if that perpendicular motion is a result of driving off a cliff, I guess I have ignored that back at the motor shaft

Not Torque .... Mechanical power.... they are different things... you can't have forgotten this already you already came at least that far in previous posts.

Originally Posted by major

On the shaft of a motor, even if there is torque, if it is stationary (zero RPM), the mechanical power is zero....

Force (or torque) can exist without power.

Originally Posted by major

In physics, power is the rate at which work is performed or energy is converted.

from:

http://en.wikipedia.org/wiki/Power_(physics)

That is what we are talking about

Following your own link above on power under mechanical power when you read it you find:

Note that only motion that is along the same axis as the force "counts", however; motion in the same direction as force gives positive work, and motion in the opposite direction gives negative work, while motion perpendicular to the force yields zero work.

When you invoke 'mechanical power' You bring with it the mandatory picking of a frame of reference and automatically in 'mechanical power' ignores all motion perpendicular to the applied force... in addition to all the other types of power invoking 'mechanical power' also ignores.

[major]

Originally Posted by IamIan

When you invoke 'mechanical power' You bring with it the mandatory picking of a frame of reference and automatically in 'mechanical power' ignores all motion perpendicular to the applied force... in addition to all the other types of power invoking 'mechanical power' also ignores.

O.K. I see what you are saying. But what is the motion perpendicular to the frame of reference which is motor output to which you refer? Let's say our EV is an elevator instead of a car. All travel is up and down. This is accomplished with an electric motor, pulley and rope. Is there work done moving the elevator up 100 feet? Is there mechanical power delivered from the motor to lift it those 100 feet?

Is this the type of perpendicular motion to which you refer?

Regards,

major

[PhantomPholly]

It seems to me that all the confusion comes from the fact that Physics does not consider that any "work" has been done unless something moves.

Thus, if you stand for an hour exerting a 100 lb upward force to hold barbells in the air, you have not done any "work." Tell that to your arms!