Timeline for Physical Variables of Circular Motion
Current License: CC BY-SA 3.0
13 events
| when toggle format | what | by | license | comment | |
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| Jul 13, 2013 at 16:23 | comment | added | Justin L. | babou I so concede that in many ways you can interchange concepts like frequency and energy in order to reveal that they are manifestations of a deeper concept/represent the same deeper thing. | |
| Jul 13, 2013 at 13:25 | comment | added | babou | There are two issues. One is the way I reason about problem: I try to reduce complexity by considering as "the same" quantities that are in a simple fixed relation in the context of the problem. It may indeed be seen as abusive from a more general perspective, and pedagogically unwise. But then, it is precisely what earlier scientists have done unwittingly in the past, because they were not yet able to make a difference, possibly using a "universal" constant to adapt dimensions. That did not keep them from doing good science that is still usable in their terms, obsolete as they may seem today. | |
| Jul 13, 2013 at 12:52 | comment | added | Saurabh Raje | Is it that you think it is a subtlety which the asker is not looking for? Or is it something you have different thoughts about, ie you disagree? Moreover, what is the context of the mention of old science? Is there any new theory presented which dominates newtonian understanding of circular motion? | |
| Jul 13, 2013 at 12:49 | comment | added | Saurabh Raje | @babou, I am sorry, but I must confess I didnt get that. What do you mean by, " I do think the issue is fundamental both from the point of view of reasonning about problems, and, even more, from a historical perspective, as I do not believe that, in general, new science invalidates old science within its context of applicability."? | |
| Jul 13, 2013 at 12:31 | comment | added | babou | @SaurabhRaje I took your comment in. Does it satisfy you as it is ? I do think the issue is fundamental both from the point of view of reasonning about problems, and, even more, from a historical perspective, as I do not believe that, in general, new science invalidates old science within its context of applicability. But this requires more discussion than we can afford here. BTW, if anyone has a pointer to good texts on this issue, I am taker (especially on the Internet). | |
| Jul 13, 2013 at 12:20 | history | edited | babou | CC BY-SA 3.0 | added 194 characters in body |
| Jul 13, 2013 at 12:01 | comment | added | babou | Of course they are obviously different from a dimensional point of view, so my statement may be misleading pedagogically. My point is different: can a change in one be physically distinguished from the other in that setting. For example, I guess many physicist talking about light would interchangeably talk of frequency or energy, but they have different dimensions. You will tell me that Planck constant $h$ is a "constant". But here the radius is a constant. Other example: people could do physics limited to earth surface without distinguishing mass and weight. How constant is a constant? | |
| Jul 13, 2013 at 11:15 | comment | added | Justin L. | They are as "different" as, say, Current and Voltage given a fixed resistance. Yes, the magnitude of current and voltage are indistinguishable up to a constant, but they are definitely physically different things with different dimensions. It would be misleading to say "current and voltage (in fixed resistance) are essentially the same thing, up to a multiplicative factor which is the resistance." | |
| Jul 13, 2013 at 11:13 | comment | added | Saurabh Raje | These things are physically different as in, when you say angular velocity/acceleration/displacement, you imagine/think about the angle that has been covered. Whereas, when you say tangential velocity or acceleration, you think of the displacement in metres, that is, displacement in a curve. So, the dimension of length is there, whereas there is no dimension of length in angular diplacement/velocity/acceleration. | |
| Jul 13, 2013 at 10:55 | comment | added | babou | The setting of this discussion is that we have a circular motion. The definition of a circle implies that the radius is constant. Then the two concepts are essentially interchangeable for reasonning. This is of course wrong when the trajectory deviates from a circle. I am not sure what it means for two things to be physically different in a context where they cannot be distinguished in any significant way. This is really a fundamental point about science. Maybe I should start "On a circular trajectory ..." | |
| Jul 13, 2013 at 10:35 | comment | added | Saurabh Raje | "Tangential acceleration and angular acceleration are essentially the same thing, up to a multiplicative factor which is the radius." Do you want to say that they are proportional? That is right of course, but I am sure that physically, the two are quite different. And they are as different as tangential velocity and angular velocity (which again are proportional with a factor of r). | |
| Jul 13, 2013 at 9:49 | history | edited | babou | CC BY-SA 3.0 | added 572 characters in body |
| Jul 13, 2013 at 9:29 | history | answered | babou | CC BY-SA 3.0 |