Hi, I'm trying to understand whether when you have a question to do with a rotating disc with two masses attached, is the inertia of the whole system taking into account the attached masses or are they simply 'dumb' tensions, and so the actual masses attached don't matter?
so for this scenario is 1 or 2 the correct way to work out the angular acceleration of the disc?
@0celo7 It won't be so long once you already know the right approach. Our conversation was long because I was making sure everything you said made sense.
You can't expect to have an off the cuff chat discussion of a complex issue go as smoothly as a well-oiled tutorial post.
The question is about the WHY of having a universal speed limit (speed of light in vacuum). Is there a more fundamental law that tells us why this is?
I don't ask why is the speed limit equal to $c$ and not something else, but why is there a limit at all?
but if you're working out the angular acceleration of the disc and the masses are also moving linearly as a result, do you need to take them into account by MR^2?
@e__ the equation $\tau_{\text{disc}} = I\alpha_{\text{disc}}$ only cares about the moment of inertia $I$ of the disc. The masses attached to the ropes enter in through the forces (hence torques depending on your pivot point) they exert on the disc through the ropes' tensions
@FenderLesPaul Lots of "philosophy" questions become physics questions when you go one level deeper. Given electricity, why does magnetism exist? In the 1800's that was a philosophy question; after SR it could be derived.
As far as I know, there is no explanation to that question, but maybe there is one to people who know the deeper levels.
@FenderLesPaul for sure, stats show a lot more next week than this week
@FenderLesPaul For domestic students, almost every school seemed to send out at least some acceptance as early as Jan. 30, or I at least had insufficient stats to conclude they for sure were not
almost definitely by the end of the first week of February though
@dmckee Suppose I have a rope connected to the center of a pulley and a rope on the pulley. The rope on the pulley has both ends connected to something.
If I pull the rope attached to the pulley and the system is in equilibrium, will the line of action of the pulled rope bisect the angle created by the fixed rope?
@0celo7 I think you have to assume frictionlessness of the pulley to get an exact answer, but sure: consider the component of tension transverse to the roped holding the pulley.
@dmckee dont feel bad, SCM systems are all very complex in theory. they are similar to mapping out independent/ dependent timelines which branch and merge. has reminded me some of the many-worlds interpretation. except even more complicated with merging.
@dmckee I had the (retrospectively invaluable) idea to switch to using Gentoo as my only desktop OS late in high school (what an experience then....). Now I ended up as the "Linux guru/troubleshooter" in the HEP group. I hope my rec letter writer mentioned it...
I hope it bodes well when applying to the appropriately relevant departments
Interestingly, I am by no means an expert on many "Linux" things, people in HEP groups just tend to have fairly straightforward problems/questions that are answered by simply having experienced the problem before
I've taken one group of students to the APS April meeting (one was giving a talk in a dedicated undergraduate science session), and sent others to the Missouri Academy of Sciences (which is a dinky regional conference with mostly undergrads).
@dmckee nice, it would be cool to hear more of their experiments, maybe they could put them on web sites somewhere or something... actually have been toying with an idea for awhile, may write it up sometime myself...
@GBeau I supervised several machine while I was a grad-student and post-doc. It's makes you a valuable guy to have around a project, but it doesn't get you that faculty interview.
@FenderLesPaul The deal is this: lots of little school need to get their students doing something that looks and feels like research. So they gang together to provide a venue, and give it a good name.
@dmckee Suppose we have some beam that is connected by a pin to something. By "the force on the beam" we just mean the third law partner to the force on the pin, right?
