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1. Misc. Looking for help calculating heat transfer for PEX ground loop project

What about installing an automatic waterer (or several)?
2. I Sonoluminescence experiment -- help please

I remember doing this a long time ago in school and being frustrated by it. Turned out that we did it correctly but we couldn't see it by looking at it directly - we had to use peripheral vision. You could try that, or try taking a long exposure photograph if possible.
3. Perspective Art of the Ancients

Here's a few guesses - It was an aesthetic or stylistic choice not to have or want paintings to be as realistic as sculpture - Surprising as it may seem since the ray model of light was understood, maybe no one had yet applied it to artwork. Heck, it wasn't until Brunelleschi published his book...
4. I Error Propagation in Measurements

Three options to consider: 1) Simply evaluate your function using measurements that result in the highest and lowest possible values, in this case calculate area given by the maximum probable measurements and the minimum probable measurements. The difference in these values will be roughly...
5. I Why does Kepler's Third Law exist?

@Martyn Arthur, if you can find access to, or purchase for yourself, the book Physics, The Human Adventure by Horton and Brush you'll find a nice discussion of Newton's synthesis of Kepler's laws that uses only algebra (but only addresses circular orbits) in Chapter 11. Further, the discussion...
6. B This rocket physics problem seems unrealistic

In case it's useful, you can get engine data here: https://www.thrustcurve.org/
7. B Question about Stereo Sound while listening to a Song by the Beatles

Instruments and vocals are recorded to different tracks that can be panned left or right. Sometimes the pan is subtle and other times it can be panned completely to one side, or even changed to give a sort of 'dizzying' effect.
8. B Seeking Astronomy Tables

Well the ephemerides (had to look up that plural!) that I've looked at don't include quadrature which was surprising. I don't think I'm going to spend money to get data for this one assignment, but I did find a Stellarium script that can toggle this information. For anyone that this may help...
9. B Seeking Astronomy Tables

...is definitely the keyword search that I needed. Thanks!
10. B Seeking Astronomy Tables

Hi everyone, I'm looking for a database of planetary events similar to this resource but that has a longer span of time that can be accessed (the site goes back to 2009). I haven't had success in my google searches. Does anybody know where I can find this information? In particular I am...
11. COVID Reaction to COVID-19 Vaccine (or what to be prepared for)

I had the J&J about six months ago and it gave me what felt like a slight overnight fever (I woke up but I didn't get out of bed to measure it). No fever in the morning, but I felt fatigued with some mild body aches the next day and I had a very tender arm at the injection site for roughly a...
12. Geometric Construction (bisecting an angle with a compass and straightedge)

This is great. Thank you. I've downloaded it and added it to my folder that contains all of my notes from studying these early works (which includes the works of Archimedes). I'm looking forward to reviewing it.
13. Geometric Construction (bisecting an angle with a compass and straightedge)

I had a vague recollection of reading about that and I figured that if I mentioned it you'd be able to confirm for me if it was in Hartshorn or elsewhere. Thanks!
14. Geometric Construction (bisecting an angle with a compass and straightedge)

Yes, if supplemented I think that could work. I agree with you that seeing a (typically) algebraic representation in a geometric way can offer insight and the example you described above is one of the ones that our small department has shared with students. Useful? I suppose that depends on...
15. Geometric Construction (bisecting an angle with a compass and straightedge)

That comment was driven mostly by the opinion you expressed here: Which I took to mean that Euclid should be the primary text for HS geometry. By 'intuition for geometry' I meant the ability to take separate simple facts and use them to develop a proof (i.e. to do what Euclid does). I think...
16. Geometric Construction (bisecting an angle with a compass and straightedge)

My impression is that the Common Core is pretty widely adopted. I like the Common Core in principle. In reality there is too much to learn everything well and, because I see students that come from a wide variety of different districts, the things that (I can infer) are omitted from the...
17. Geometric Construction (bisecting an angle with a compass and straightedge)

I think elementary school would be too early because algebra I skills are assumed for much of the text. For middle school I think it can be excellent. Our middle school math teacher uses Serra for a geometry course for students who are already comfortable with algebra and I think it has worked...
18. Geometric Construction (bisecting an angle with a compass and straightedge)

Here's an online resource that I'd recommend, especially if you're using something like the Green Lion Press version which has no commentary. Navigate to each book by the Roman numerals at the top. That is a great book. I'm using Serra's book this year and I like the spirit of it. It is...
19. Geometric Construction (bisecting an angle with a compass and straightedge)

I meant to stay straight edge and compass. A ruler is (obviously!) a measuring tool, not a construction tool.
20. Geometric Construction (bisecting an angle with a compass and straightedge)

But a protractor is a measuring tool, not a construction tool. If we allow measurement then angle trisection is trivial. Interestingly, angle trisection is not possible with a ruler and compass alone. I'm teaching HS geometry this year and the text we use has a chapter dedicated to...
21. Life's great mysteries (things that make NO sense)

My college roommate freshmen year was the first seat big band drummer at school and he is the one who introduced me to Buddy Rich. So. Good. I agree with you about the majority of 'synth-sounding' drum effects. I think my point was just that electronic drums can sound good, but I want drums...
22. Life's great mysteries (things that make NO sense)

I was going to write a response about Bill Bruford but here's a better source: https://www.musicradar.com/news/electronic-drumming-pioneers-11-trailblazing-players-who-raised-the-bar-for-electronic-and-hybrid-drumming Start with Danny Carey (#2). If you like rock music and haven't heard...
23. Open Label Placebos

An interesting news article. Part of it describes how starting a treatment (say, opiates for pain) and then substituting placebo afterward (with the patient knowing) can still produce a pain relieving effect. This aligns with an interesting thing I learned from a neuroscientist several years...
24. I Good introductory book for chaos theory?

Here's some Looks great.
25. I Good introductory book for chaos theory?

If you happen to have access to John R. Taylor's Classical Mechanics there is a chapter dedicated to Chaos near the end. Obviously this will not be very comprehensive (in terms of breadth and depth), but his writing is comprehensive (in terms of accessibility!). Another accessible text that's...

27. Making physics exciting for 5th graders

One entertaining phenomena that could take up a class period or more is to have the students add a couple of drops of food coloring to whole milk on a (clean) plate (thin layer of milk). They can use any color or combination of colors, but it is good to limit them to a few drops. Then, come...
28. Does any classical mechanics textbook solve Kepler's Problem?

Orbital Mechanics for Engineering Students Howard Curtis Appendix D gives several MATLAB algorithms for solving Kepler's equation (all by Newton's method). Paragraph before the first algorithm:
29. B Could Archimedes' problem have been solved a little differently?

There is a practical problem with the volume method. The 'crown' was more like a wreath and would not have a substantial enough volume of gold to displace the water significantly enough in the vessel needed to hold the crown (without damaging it) to be confident in the measurments. When...

31. I On spherical geometry and its applications in physics

The original application was for astronomy. There's a book called Heavenly Mathematics which I enjoyed working through recently. It traces the historical development of the math of spherical trig which I found insightful for understanding the formulas you may have seen. One of the...
32. COVID COVID-19 Coronavirus Containment Efforts

I can't speak to Germany and Oregon, but here in Vermont the various outbreaks around the state mostly trace back to an outbreak in a hockey league: https://vtdigger.org/2020/11/30/is-there-a-skater-zero-tied-to-central-vermonts-covid-outbreak/ The recent uptick in deaths stems from outbreaks...
33. COVID COVID-19 Coronavirus Containment Efforts

Maybe. Maybe not. I don't think it is unreasonable to look at different time intervals and I can imagine that some folks looked into this without being motivated by partisanship. Whether or not a person has a partisan motivation behind looking at sub-intervals might be irrelevant if we...
34. COVID COVID-19 Coronavirus Containment Efforts

Perhaps part of the problem is that people are considering different time periods. When you look at the data from January there is (currently) no correlation as you point out and all states are doing poorly. If folks want to slice up the time intervals trends may be noticed. For example...
35. COVID COVID-19 Coronavirus Containment Efforts

That's a good point. I had overlooked that Goodspeed's charts are only accounting for numbers since July so they tell a different story than if we were counting from January. My mistake.
36. COVID COVID-19 Coronavirus Containment Efforts

I understand that. But the overall rates of infection and deaths right now are distributed differently. My point was that, though it may be misleading for news sources to pick individual towns/cities/counties when they say "Hey look at this case/death rate and the fact that they are...
37. COVID COVID-19 Coronavirus Containment Efforts

I'm not sure about that. Based on the second source I provided above the top 11 states with fewest cases per million are democratic (one neutral) based on the partisanship metric used, and the top 9 states with most cases per million are republican (one neutral). I'm referring to the most...
38. COVID COVID-19 Coronavirus Containment Efforts

Obviously looking at single towns, or perhaps even cities, there are going to be outliers for in either direction from the national trend by political partisanship. But, in the US at this particular time, there seems to be a correlation between political partisanship and both infection and...
39. Uncertainty of the Best Value from a Multiple-Trial Experiment

An excellent resource is John R. Taylor's An Introduction to Error Analysis. I didn't find it until after I was done with college, but I like the balance he strikes between informality and rigor. There is a short chapter on the method of weighted averages described above.
40. Nouns that exist only in the plural

There's a Fela Kuti song called Equalisation of Trouser and Pant which was the only reason I questioned this statement. Indeed, according to Merriam-Webster 'trouser' is a noun though it is 'usually used in the plural'
41. Intro Physics What Basic Physics Book?

https://www.amazon.com/dp/0534377289/?tag=pfamazon01-20 This has a more detailed, but introductory, treatment than you'd find in survey-type texts.
42. B Why does the radius of a unit circle need to be 1?

Others have already pointed out that this is just a matter of convenience. I'll just add that early trigonometry (and spherical trigonometry) used a radius of 60 (see Ptolemy's Almagest). That was a convention left over from the Babylonian astronomers. I'm not sure when the unit circle was...

44. Measuring Reflectance with a Digital Camera

I finally had a chance to think about this again after several weeks. I was much more careful in setting up the conditions for the camera but still wasn't able to get results that I trusted. So I bit the bullet and got the app so I could compare the results. I tried three surfaces: cardboard...
45. Measuring Reflectance with a Digital Camera

That's a cool idea. I had to go to the hardware store today anyway so I checked out the colorimeter. I used to work in a paint store as a teenager and used one for color matching. I couldn't remember what information was available in the menus, but at this particular store it is limited to...
46. Measuring Reflectance with a Digital Camera

I agree that for the students that is the important concept. I was asking about the accuracy for my own benefit. But... if there are some simple things that can be done to improve the accuracy and reduce bias in measurements, why not do it? I don't skip teaching students how to zero a...
47. Measuring Reflectance with a Digital Camera

Thanks for the thoughts! As per the saturation issue: on the 0-255 scale that is used how high do you think is too high? I took several photos of paper in direct sunlight and had values for average intensity around 245. Indeed, I thought of that. Before I got the gray card I tried using a...
48. Measuring Reflectance with a Digital Camera

Background: This fall our initial plan will have high school students on campus 1 day per week and working remotely for the remainder of the week. I'm trying to plan for some at-home labs and projects. I came across http://albedodreams.info/how_to/how-to-calculate-albedo-yourself/ site which...
49. I Confused about Mercury Barometers

Yes, and I can verify that the weight I had to support with my hand was certainly greater than the weight of the tube itself!
50. I Confused about Mercury Barometers

There's nothing more convincing than experimental evidence. When I teach this subject I start with a demonstration using "Pascal's apparatus" which shows that the force exerted by a column of liquid with a given base area depends only on the height and not the volume (and thus not the weight)...