author=bistander link=topic=4603.msg111141#msg111141 date=1711694698
Where is the distance from the center of rotation used to derive the torque value from a force measurement?
You do not need the distance from the center of rotation to obtain the torque value being imposed on the outer rim of the rotor.
We are not measuring ft/lb or newton meters of torque. We are measuring the torque being applied to the outer rim of the rotor.
The rotor could be any diameter, but the torque imposed on the outer rim would be the same regardless.
The only thing that would change, is the ft/lb or newton meters of torque value. The torque value on the outer rim of the rotor would remain the same.
You are mixing up torque and foot pounds of torque etc. They are not the same thing.
I decided to ask your belove chatGPT what an applied force to a rotating body is called
Guess what it said
The force applied to a rotating body is called torque. Torque is a measure of the rotational force applied to an object, causing it to rotate around an axis.
I then asked it this--is an applied torque over distance energy ?
It's answer was
when torque is applied over a distance and causes an object to rotate, work is done, and energy is transferred.
I am not sure why you cannot see that we were graphing the value of torque being applied to the outer rim over a distance of a rotating body.
I said-quote: "My graphs show torque over a distance in a rotating system."
You said in post 72 -quote:
That would be your graphs show torque vs angle (or radians). And that is not energy.I once again aske your beloved chatGPT- is torque applied to a rotating disc over distance energy
It's answer-
Yes, when torque is applied to a rotating disc over a distance, it involves the transfer or conversion of energy.
Work: When torque is applied over a distance (angular displacement), work is done on the rotating disc. Work, in this context, is the transfer of energy that results in the disc's rotational motion. The amount of work done depends on the magnitude of the torque applied and the distance over which it is applied.
So, when torque is applied to a rotating disc over a distance, it involves the transfer of energy, as work is done on the disc to make it rotate. This demonstrates the connection between torque, angular displacement, work, and energy in the context of rotating systems.
In post 74, you said:
Only the force in the direction of motion or displacement enters into the work formula.
I must say, if the torque is being imparted on the PM that is fixed to the rotating disk, in which direction do you think it was going when each measurement was taken in the graphs?
Obviously, the electromagnet, which is fixed into position, is pulling the PM on the rotor toward it, in a radial arc from point A to point B-the direction of rotation, as clearly shown in the diagram posted.
You also said in post 74 Quote:
Force over distance in rectangular coordinates or torque over angle in polar. But not a mix of the two.
I never mixed the two. It was you that was unsure how the measurements were taken, not me.
I don't see that and without that I fail to comprehend how you can call a force measurement torque.
Once again, because a force applied to a rotating body is called a torque. not foot pounds of torque, not newton meters of torque, just a torque.
That torque can be measured in grams, pounds, newtons-what ever you like,
When we were all testing this motor, we wanted to know the difference in applied torque onto the rotors outer rim during the brief on time of the coil, at the same P/in to the coil, over the same distance of rotation, between the two types of motors. By graphing the torque curve as we did, we could calculate the average torque applied to the rotor in both the motors, regardless of what diameter each persons rotor was.
Your helpful diagrams stated distance from A to B indicating linear.
No it did not.
How on earth do you get linear from a diagram that shows a magnet traveling from point A to point B on a rotor ?
The diagram says- graphs show torque over distance measured between point A and B of the !rotating mass!, which obviously means that the distance between point A and point B is the curved path of the rotating PM, which is fixed to the rotating mass.
How was I to know you had used a string to get an arc around the circumference, until you just told me.
Well how was I to know that you didn't think I new what I was doing, when i've been doing this type of thing for 40 years.
How else would you graph a torque curve using multiple static measurements over a curved path?
It would seem like you decided I was wrong, before you even knew how the test was carried out.
And if the radius was used to calculate torque from the force measurements, I could then see a "torque curve".
Once again, the radius is not needed to obtain the torque curve being imparted on the outer rim of the rotor.
The rotor could have a radius of 100mm or 500mm, but the torque being applied on the outer rim of the rotor would be exactly the same in both cases.
Once again, we refer to your beloved chatGPT
Question-what is static torque
Answer-
Static torque refers to the torque applied to an object that is not in motion, i.e., it is static or stationary. It's the torque exerted on an object without any movement or rotation occurring.
In practical terms, static torque may be important for various reasons:
Assembly and Fastening: When assembling components, especially in engineering and manufacturing, static torque is often applied to fasteners (such as nuts and bolts) to ensure they are tightened to a specific torque specification.
Calibration: Static torque is used in the calibration of torque-measuring instruments or devices, ensuring their accuracy by applying known torques to them while they are stationary.
Preload: In mechanical systems, such as bearings, static torque might be applied to create preload, which helps to reduce backlash, improve rigidity, and enhance the overall performance of the system.In summary, static torque is the torque applied to an object at rest, and it finds applications in various fields such as engineering, manufacturing, and mechanical systems.And as chatgpt said, "Energy, or work done, in rotational systems is the product of torque and the angle through which the object rotates
Which is exactly what the graphs and diagram show.
It shows the torque value being imparted on the PM, that is fixed to the rotating disc, and so the PM will change angle slightly to that of the electromagnet, through each torque measurement point in the graph.
I really am confused as to why you find this hard to understand.
I still think you are mixing up torque with the likes of foot pounds of torque, or newton meters of torque, but they are not the same.
One more question for the almighty chatGPT
if you are pushing down on the peddle of a pushbike, but the peddle does not move, are you applying a torque upon the peddle ?
Answer:
Yes, if you are pushing down on the pedal of a pushbike but the pedal does not move, you are indeed applying torque to the pedal. Torque is the rotational force applied to an object around an axis, and when you push down on the pedal, you are applying a force that tends to rotate the pedal around its axis of rotation.
Brad
Never let your schooling get in the way of your education.
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