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The question:

https://physics.stackexchange.com/questions/227391/trajectory-of-projectile-launched-from-planets-surface

raises an interesting issue. The SE system allows for Answer your own question posts as a sort of mini-blog way of posting interesting information. I think this is a good thing and I've used it several times myself. However here we have a case of an Answer your own question post being used to provide the solution to a worked example.

The trouble is that we have long regarded worked examples as falling into the homework-and-exercises category. If I posted the original question and sat back to await answers my question would be rapidly closed. So what should we do in this case?

Looking forward, if this question is OK then it establishes the principle that worked examples can be answered - if only in an Answer your own question context. That would open the doors to, for example, people using the site to provide answers to the questions in MTW, Wald, etc. Actually I'm quite sympathetic to answers to worked examples being available on the web, though I don't think this is the right place for them.

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  • $\begingroup$ I think that defeats the purpose of exercises. They are to challenge you. For example, in my economics class, some of the problems were essentially derivations of basic cases that could be found on Wikipedia. Students just got 100% because they could copy it from the website. $\endgroup$
    – Stan Shunpike
    Jan 4, 2016 at 7:03
  • $\begingroup$ I also like SEs usual policy of "show some effort" because it implies that homework help isn't about answering hw questions but about clarifying confusing conceptual points within an exercise. I think if you allow people to post solutions, it focuses it away from the concepts and more to treating it like a hw problem, which I personally dislike $\endgroup$
    – Stan Shunpike
    Jan 4, 2016 at 7:06
  • $\begingroup$ I did this Q & A myself just reasently too, this might be also used as an good or an bad example; physics.stackexchange.com/q/227309 .. Why I did this? -I wanted to send the info to the author who asked this in his paper, and now I can simply provide a link. $\endgroup$
    – Jokela
    Jan 4, 2016 at 7:26
  • $\begingroup$ @JokelaTurbine Your question seems to ask for a physical explanation of a feature, so I think it's likely to be fine. $\endgroup$
    – David Z
    Jan 4, 2016 at 10:05
  • $\begingroup$ Don't just think MTW and Wald, which are generally only read by students who are committed to learning the subject. Think Halliday & Resnick and such books used primarily by non-physicists looking to pass their required physics course by any means necessary, with as little effort as possible. $\endgroup$
    – user10851
    Jan 4, 2016 at 12:08
  • $\begingroup$ I generally don't see a problem with well worked exercise questions, even though I couldn't give an example of this case that was well worked. I am not sure that having poorly worked exercise problems like the one mentioned here sticking around adds to the quality of the site, though. It is certainly not helpful if, as Chris White suggests, these are just pass-exams-at-all-cost solutions that show no physical insight and are not trying to stimulate intellectual growth. $\endgroup$
    – CuriousOne
    Jan 5, 2016 at 18:36

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This is something to take into consideration when we reformulate the homework policy. (It's happening. Slowly.) For now, I'd say just judge the question on its own merits, i.e. without considering the answer. If you saw this question posted by itself, without an answer, would you consider it to be off topic as homework-like? If so, go ahead and vote to put it on hold.

I'll also take a look at the answer and decide according to our usual criteria whether it should be temporarily deleted, as we generally do to complete answers to homework-like problems.

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  • $\begingroup$ It's pretty diffucult to evaluate the said question if it's a "homework" at first view I felt it's not, as there isn't any particular case calculate. But on second view, I think it is, as there is really nothing else to explain, than do the math. I just made some new approach to this questions making here; meta.physics.stackexchange.com/q/5203 as it seems that these unsuited questions are sucking huge amount of resources here. And the present "how to ask" quide leaves quite wide grey-zone. $\endgroup$
    – Jokela
    Jan 4, 2016 at 11:12
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    $\begingroup$ We temporarily delete complete answers to homework-like problems because we want the OP to have a chance to figure out the answer with just hints. But if the OP posts the answer I see no value in temp-delete. Not sure whether "OP has figured it out" is a criterion that is considered when deciding a full solution can remain? I thought it was. $\endgroup$
    – Floris
    Jan 6, 2016 at 20:28
  • $\begingroup$ @Floris I'd go the other way. The reason for eventually restoring complete answers is because the answerer did the work in an earnest effort to help a stuck questioner. In the case of a self-answer to a homework-like question the OP's real reward is figuring out the problem and all of our usual arguments about not wanting this site to be about solving textbook problems take precedence. Everything "in my opinion", of course. $\endgroup$
    – dmckee --- ex-moderator kitten
    Jan 10, 2016 at 3:58
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    $\begingroup$ @dmckee I respect your opinion but disagree with the premise. I suppose I think a repository of worked examples is a good thing and you don't believe phys.se should ever be that. $\endgroup$
    – Floris
    Jan 10, 2016 at 4:03
  • $\begingroup$ @Floris Oh, I'm sure that Physics could become that. I just think it would harm the site, but that is a personal view. $\endgroup$
    – dmckee --- ex-moderator kitten
    Jan 10, 2016 at 4:09
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    $\begingroup$ @dmckee let's agree to disagree. $\endgroup$
    – Floris
    Jan 10, 2016 at 4:24
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It says nowhere that this site is restricted to only theoretical or conceptual Physics questions only, and everything related to physics problem solving is banned.

Tell me if I'm wrong about this and point me to the reference, or make a new thread to discuss it to change the scope officially.

Let me quote Mew's comment below this answer from another related question:

I don't believe that providing complete solutions is detrimental to students, and in fact I believe the best way for students to learn the basics of physics is to look at as many complete solutions as possible. I believe this method is far superior than asking the student to attempt to solve the problem by themselves. When a student has seen many problems, I believe they will have no trouble in developing an intuition to solve far more physics problems, and will have much more refined thought process than the students who went off on tangents trying to solve problems using unconventional methods – Mew

I agree with him.

When I was a student I always got A+ for all may physics exams in high school, because they always included problems of types the teacher already showed us how to solve (not the same problems, but with different numbers and conditions).

Due to my performance I always went to Physics competitions but I weren't too successful in them initially. The reasons: the problems they gave me to solve was of types I never seen before.

Let me show you an example. Electric circuits. Most students learn how to calculate the resistance, inductance and capacitance when these elements connected in series or parallel. But what do you do when you are faced with an arbitrary graph of capacitors, resistances or coils which you cannot rearrange into the usual series parallel structure? I was flinched by these tasks, I didn't even know how to start at all!

Eventually after sending and receiving lots of letters (I didn't even had internet that time), discussing with peers other competitors and teachers, I managed to learn helluva lots of tricks and tips and approaches you can't find in any text book, which eventually got me to the final rounds and took the 4th prize.

I don't have 10k+ reputation so I can't open the linked question in the example. But I think catch-all questions self answered or not, that ask "What approach should I use when solving problems of this class" (without actual numbers plugged in) would be very useful for students who are preparing for competitions or exams, engineers writing simulation software looking for the methods, etc.

Then again if this site isn't for helping students learn the methods and know/how of problem solving than we should point that out in the tour and the help/ontopic as well.

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  • $\begingroup$ This can be true but this is not the place to post such question. There is indeed given the guidelines under How to Ask; this site is not built to promote or tolerate such sort of questions. The main criteria of asking a question is to ask about some concepts and not just some numericals, no matter how helpful it may be. In fact, to the contrary, it degrades the quality of the site (we aren't Yahoo!) and doesn't provide any insight to most of the users here generally. There is no need to ignite the debate - we don't want homework questions. Never!! $\endgroup$
    – user36790
    Jan 8, 2016 at 2:12
  • $\begingroup$ ...and everything related to physics problem solving is banned. I think most would argue that the HW Meta post does ban problem solving, which is why we regularly close homework-like questions as off topic. $\endgroup$
    – Kyle Kanos
    Jan 8, 2016 at 11:12
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    $\begingroup$ The pedagogical literature consistently reports that studying worked examples is not only a not a good way to learn physics, it's one of the worst. Getting conceptual help when you are stuck, on the other hand, is an efficient way to learn because it forces you to confront misconceptions and holes in your understanding. But that is a interactive process, not an archive. $\endgroup$
    – dmckee --- ex-moderator kitten
    Jan 10, 2016 at 3:56
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    $\begingroup$ @dmckee Can you provide links to that pedagogical literature? Internet says the opposite... They seem to agree that they are very useful for novices and but less effective for those with prior knowledge. $\endgroup$
    – Calmarius
    Jan 11, 2016 at 7:25

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