# Replacing the homework policy 1: what existing questions should be on/off topic?

TL;DR: post examples of current questions which are edge cases for the new policy, look through the list, and

• vote answers UP if you think they should be ON TOPIC
• vote answers DOWN if you think they should be OFF TOPIC

Also, if you feel motivated, fill out this questionnaire about the answers.

When we last left the ongoing examination of our homework policy, the community had come to something of a consensus that certain low-effort questions asking for calculations should be off topic. In addition, I've been watching actual question closures over the past couple months since we had that discussion, and I see more and more questions getting closed for displaying unacceptably low effort, whether using the existing homework-like close reason, or a custom reason written in a comment.

I think it's time we start formulating a new policy.

This new policy, along with one or two associated close reasons, will prescribe how we should decide whether questions are off topic for being low-effort and/or being calculation requests. It will replace the current homework policy, and in the future, we will use the associated close reason(s) for homework questions, instead of using the existing homework-like close reason (which will no longer be active).

What I have in mind is a process in 4 steps, of which this is the first:

1. Collect examples of questions that should be on topic or off topic under the new policy.
2. Prepare and edit a draft of the new policy that implements the consensus on the examples as well as possible. This may take a while.
3. Decide on the wording of one or two new close reasons that will be associated with the new policy. Two reasons would be an option in case we want both low-effort questions and calculation requests to be off topic and we can't come up with one reason to cover them both.
4. Make an official post with the content of the new policy, deprecate the current homework policy, and swap the new close reasons in for the existing homework-like close reason. This is the easy part.

# 1. Collecting examples of on/off-topic questions

In order to guide the development of a new policy, I think it will help to have many examples of questions that should be on topic or off topic. So I'm making this post to solicit these examples from the community.

Here's how it will work: each answer should contain a link to one question that is currently on the site. Vote up each answer if you would like to see that question be on topic under the new policy (that we are going to write), and vote down if you think the question should be off topic under the new policy.

Please vote based on how the question is currently written, not based on how you think it could be written if it were improved.

It doesn't matter so much whether the question is currently open or closed. If you have feedback arguing one way or another for a particular link, leave it in the comments on that answer.

For a lot of questions, the decision is obvious. We don't really need to post those. What I'm most interested in are "interesting" cases, such as questions which are currently on topic but which you'd like to see be off topic under the new policy, or vice versa. Borderline questions, which are not clearly on-topic or off-topic, are also good candidates for posting here. For inspiration, you can look at our previous discussions on this topic:

and so on, e.g. linked and related questions in those.

The consensus that emerged from the last meta question is represented by rob's answer, which suggested the following:

Questions which attempt to outsource tedious calculations to the community, without any broader context, are off-topic.

I recognize that a key word here ("tedious") implies a value judgement, and there's a bias in writing these guidelines towards "objective", judgement-free criteria. That bias is flawed, which is why we have human moderators and the opportunity to discuss some decisions with them.

Use this as a starting point to help judge which questions are likely to be edge cases and how you would vote on them.

• I mean... I guess it can't hurt to revise things with everything we've learned since the last time, but man I'm worn out on talking about homework. Maybe to put an optimistic spin on things, it's good that things are all running well enough elsewhere that this is all there is to discuss? – tpg2114 Apr 5 '16 at 15:59
• @tpg2114 Yeah, I understand being tired of it. We have beaten this topic to death. But we didn't really have an actionable plan until now. I'm hoping to finally put the issue to rest by doing this. – David Z Apr 5 '16 at 16:15
• I've actually got a bad case of fatigue on this. I'm too tired to think and write carefully about it. It's clear that the current policy is too nebulous and not well understood by all active members much less new askers, so I suppose it still needs doing, but ... uhg! – dmckee --- ex-moderator kitten Apr 5 '16 at 19:30
• @dmckee Maybe we can team up to do our best Statler and Waldorf impressions from a virtual balcony on this whole thing. – tpg2114 Apr 5 '16 at 20:11
• "I'm hoping to finally put the issue to rest by doing this." - kudos for optimism and effort. I wish I could be more optimistic and less cynical but I suspect that rest is not in the future of this issue though it might asymptotically approach it. – Alfred Centauri Apr 5 '16 at 22:16
• @AlfredCentauri I'm willing to bet that eventually, hopefully this time, we can come up with a clear policy that makes all of us grumpy folks happy and is clear enough that we can point somebody to it and say "This is exactly why we closed it" and they understand and acknowledge that their question should have been closed under the policy. I suspect, however, that we will never rid ourselves of people who complain that the policy exists at all and are upset we refuse to answer their questions. – tpg2114 Apr 5 '16 at 23:04
• My $0.02: hopefully the notion that "how to solve this isn't a concept question" would be cleared up with whatever comes of this. – Kyle Kanos Apr 6 '16 at 1:56 • I agree with @tpg2114 that we will probably never see the end of people complaining that we don't answer their questions, no matter what our policies say. This update is targeted at the existing members: we should have clear guidelines regarding what to close. – David Z Apr 6 '16 at 5:32 • Ultimately, I do not think it is possible to have a well defined algorithm that will determine what is homework/homework-like or not. I rely more on my spidey-sense tingling that the OP just wants an answer to write down. It is ultimately a community-standards thing like smut - you know it when you see it. The problem for many posters running afoul of the policy is that they haven't seen a million similar questions before in problem sets, yet most of us have. And, before the internet, we beat on the problem and developed our physics intuition/tools that way. – Jon Custer Apr 6 '16 at 14:34 • @JonCuster That kind of describes our existing policy: we tried to define some criterion describing what we should treat as homework-like, but we never really pulled it off and wound up relying on spidey-senses. The thing is, everyone's sense was different, and a lot of people gave up on trying to decide whether something was homework-like and just closed questions as low-effort. We're basically trying to make that official now, so that we don't even have to decide whether something counts as homework-like or not in the first place. – David Z Apr 6 '16 at 15:08 • @DavidZ - Oh, I think I got the general gist of it. Our biggest problem (and I'm a relative newcomer here I readily admit) is that it is unlikely that the askers of homework-like questions would be satisfied even with an infallible algorithmic process (they would spend more time reverse-engineering the algorithm to tweak their question than they would on working through the physics). But maybe I'm just a cynical old scientist/manager at this point... – Jon Custer Apr 6 '16 at 16:16 • Is there a problem with bringing back the old "low effort/no research" close reason that used to exist? Or just having a generic "Not up to expected quality standards" that can be used for all kinds of questions? – tpg2114 Apr 6 '16 at 17:07 • @tpg2114 I don't remember us ever having that close reason. Any chance you can find a question that was closed with it? – David Z Apr 6 '16 at 17:18 • Perhaps we need to create new StackExchange site for homework help for all the different subject (physics, chemistry, biology etc. etc.) and then impose strict rules for posting homework there. This then keeps non homework questions free from being judged using inappropriate homework standards, also the responses can be more adequate. In general, you go about helping a student with his/her homework in a different way than responding to a non-homework question. – Count Iblis Apr 13 '16 at 0:38 • Everyone please notice how DavidZ is not calling this the "homework" policy any more. The fact that we're using the word "homework" in the close reason and help center is one of the big problems here. Let's try to stop using that word. See my previous post about this issue. – DanielSank Apr 13 '16 at 7:58 ## 23 Answers Sound pitch of glass with water This is not a homework or homework-like question, it's not a calculation request, it's completely conceptual, but the question doesn't show any prior research, or any evidence that the poster has made an effort to figure out the answer themselves. You might think that's perfectly fine. On the other hand, if you believe the poster should have shown more effort, what would you expect them to have done? (You can address this in the comments on this answer if you like.) Vote up if you think this question should be on topic under the new policy, or vote down if you think it should be off topic under the new policy. • I think that if the poster actually had no clue why it is caused it is almost impossible to do research, hence the question (which will reveal relevant names and concepts). The question itself is at least posed very clearly. I have been in a similar situation recently; I did not even find the relevant wiki article, but the question was well received. – caconyrn Apr 27 '16 at 12:45 • I agree with caconyrn : without the broad understanding of physics which graduates are expected to have, it can be impossible for a novice to know where to start looking for an explanation for such a phenomenon. I think the questioner is to be applauded for his observation and his curiosity. In any case the question should not be closed without asking the questioner for his ideas. – sammy gerbil Apr 27 '16 at 18:56 Three dimensional isotropic harmonic oscilator Hamiltonian This is an advanced question (on quantum mechanics) that shows detailed effort. It could be argued that it doesn't actually ask anything beyond "what am I doing wrong?", though. Vote up if you think this should be on topic under the new policy, or vote down if you think it should be off topic under the new policy. • I am conflicted on this one. The purpose of the site is to generate useful content. By reading that question I learned to be careful and not apply commutators of each dimension's operators to the full vector operator. I mean, I probably already knew that, but this was a useful reminder. Maybe there are so many possibly useful reminders though that questions like this should be off topic. In either case, I'm not entirely sure how the "what's wrong here" issue falls under what we're trying to construct to replace the homework policy. I guess you're just ambitious, which is great. – DanielSank Apr 13 '16 at 8:03 • @DanielSank actually, I'm somewhat conflicted on this too, for much the same reasons. I tried to word this answer in a way that avoids taking a position on the issue (with limited success, I suppose). This is one of those edge cases that I really want to get the community's input on; whether questions like this are desired to be on topic or off topic will play a big role in determining how the new policy gets constructed. – David Z Apr 13 '16 at 9:30 • Perhaps such "edge cases" should not play a large role, precisely because they're edge cases :-) Should we not focus on wording the policy to be clear for the majority of cases, those where it's clear whether the question is on topic or not? – DanielSank Apr 13 '16 at 17:44 • @DanielSank Those are not exclusive goals. Of course the policy will be worded to be clear for the obvious cases, but that still leaves a lot of freedom in how it's constructed. That's where the edge cases come in. They help pin down the specific wording. – David Z Apr 13 '16 at 18:22 • I'm just saying that edge cases maybe should not play a "big role". It's not worth losing a lot of fidelity on the 99% for the sake of the 1%. I think we agree and I'm just picking on the wording of your comment. – DanielSank Apr 13 '16 at 19:51 • The questioner has made a reasonable effort. An answer (pointing out an error in a calculation) will make him a better physicist. The answer could be instructive to others, as DS acknowledges. However, that benefit might never extend beyond the questioner and answerer. But the same could be said of any question which is judged to be clearly 'on topic' - there's no way of knowing whether any question will ever be useful again. – sammy gerbil Apr 27 '16 at 18:07 Mutual$E$force due to charged coaxial rings I think this is probably homework because it's really just asking how to solve a problem. However you could argue it's conceptual in the sense that it's asking about how to approach this sort of problem for arbitrary geometries. A belated footnote: the simplest approach I've seen to doing this requires the use of the reciprocity theorem, and specifically that the potential energy of a quadrupole charge distribution in the electrostatic potential from a monopole is the same as the potential energy of a monopole in an electrostatic potential from a quadrupole. Wouldn't answering aalong these lines count as conceptual? Vote up if you think this should be on topic under the new policy, or vote down if you think it should be off topic under the new policy. • Please let's try to stop using the word "homework". Whether or not a question is homework isn't the issue, as discussed here. – DanielSank Apr 13 '16 at 7:59 • I agree with DanielSank. I don't see any reason for distinguishing between homework and eg self-study. The issue is whether providing an answer will make the questioner (and the broader community, possibly also the answerer) a better physicist. The questioner here clearly shows effort to solve the problem and willingness to learn. He is not asking simply to avoid thinking about or researching the problem himself. Clearly 'on topic.' – sammy gerbil Apr 27 '16 at 17:37 • I'm in the small minority here, but I thought I'd voice my reason for why the downvote: The questioner isn't really asking how to approach this for arbitrary geometries. Besides being just interested in the particular case, he clearly knows how it's done in general (even if it isn't stated). How else would one code it on a computer? All this is is taking a numerical integral that one knows how to set up and asking how to solve it analytically. There is no confusion about the physics, as cute as the physics problem is. – user10851 May 18 '16 at 1:57 Extension in a vertically hanging rod This is a homework question, and the OP admits it's a homework question. However the OP isn't asking us to do the problem, they are asking about the physics behind it making more of a homework inspired question. I would leave this one open. Vote up if you think this should be on topic under the new policy, or vote down if you think it should be off topic under the new policy. • I'm not strongly opinionated on v1 of the linked question. I think it could be better if OP added more about what's confusing him, but I'm not terribly convinced that it's too broad or homework-like. – Kyle Kanos Apr 6 '16 at 10:15 • I like your comment Kyle, but then the OP would fall under the "unclear what you are asking" category, wouldn't it? Regarding that category, I think it could be split into "you need to be more specific and coherent", "you really haven't asked a question", and "this is a nonsense question". Maybe the original category is "too broad". – Bill N Apr 6 '16 at 17:30 • No work shown tho. Like what has the person done to answer the question? Its like a fine question, but i feel like w/o work it is sorta hard to accept it. As a frequent hw question asker on math se, i always try to like give a really good faith attempt. I feel if i dont post my work, people have every right to assume i did none. Showing work imo is like courteous. It shows u arent using ppl but like have worked and just need a helping hand. – Stan Shunpike Apr 7 '16 at 4:46 • It's just possible that you're defining "conceptual question" as "one to which John Rennie can give a great conceptual answer". I think the question should be edited a bit, so that it can become the conceptual question it deserves to be and then it would be unquestionable on-topic. Something along the lines of adding "A naive analysis would be to note that both rods are subject to the same downward force and assume they were each stretched by the same amount, but this turns out not to be the case." Just before the existing "Why". – dmckee --- ex-moderator kitten Apr 8 '16 at 3:21 • Yeah, I'm kind of with @dmckee that this could easily be edited into a much better question. That being said, here we want consider the question as written, not what it could be edited to be. – David Z Apr 11 '16 at 9:46 • I think I'd edit this as suggested by @dmckee and leave it open. It's silly to close a question because it's missing a single sentence which you could add in fifteen seconds. Also note that this question highlights that whether or not a post is motivated by homework is irrelevant in whether or not it should be on topic. – DanielSank Apr 13 '16 at 8:08 • @DanielSank Just seeing this now, but let me say that in order for the answers here to be most useful, I'd want people to vote down answers corresponding to questions that would have to be edited to be on topic. (I mean... technically I did ask whether people think the questions should be on topic or not, I didn't ask whether people think they should be closed or not. :-P) – David Z Apr 18 '16 at 2:18 • I fully sympathise with the question-setter : "In my defence it's impossible to show the workouts because I don't understand the situation." I had to read through the question, comments and answers twice before I understood what the problem was. Ilya's hint and answer only confused me further. If the questioner cannot understand the meaning of the question, I think it is unfair to penalise him. He is not too lazy to think, he is simply stumped by a bizarre situation. Once you understand what the question is asking, it is quite an instructive puzzle. So I think this is 'on topic.' – sammy gerbil Apr 27 '16 at 18:31 Thanks to dmckee for digging up an old deleted question asked by me a long time ago here. Here it is: Suppose a plane of mass$M$flies at constant velocity at a height$h$above the ground. If$h$is much larger than the size of the aircraft, what is the pressure increase on the ground as a function of the position relative to the point directly underneath the aircraft? I then added a heuristic way to tackle the problem (some of it was in the comments): If the velocity field were (on average) to have a radial component that decays like 1/r^2, this amounts to a source, which violates conservation of mass. But you can then imagine a sink nearby, in the limit that they get infinitely close and the sources get infinitively strong, you should get a dipole like velocity field. Then this decays like 1/r^3 at large distances. At the ground we impose zero velocity boundary conditions, the pressure should thus behave like 1/r^6 = 1/(h^2 + d^2)^3 where d is the distance on the ground from the point directly underneath the aircraft. Integrating the total pressure over the surface should yield the weight of the aircraft. If we write the pressure as A/(h^2 + d^2)^3, then the integral of 2 pi A d/(h^2 + d^2)^3 over d from 0 to infinity should equal M g. Solving for A then yields the pressure: P(d) = 2 Mg h^4/pi 1/(h^2 + d^2)^3 But all this is on the basis of purely intuitive reasoning. Vote up if you think this should be on topic under the new policy, or vote down if you think it should be off topic under the new policy. • The only actual question in what you quoted asks for the direct answer to a clearly homework-oriented problem. The following effort is nice and all but no further questions are asked. At best, the amounts to an unclear question. But the only answers I can imagine would be "Yup, that's correct" or "No, [x] is the correct way to do it". I'd call this off-topic – Jim Jun 29 '16 at 13:54 I'm going to go off the script David proposed and emphasize one point: • This programme needs to consider very seriously the role of the tag. This is, as I wrote here, one of the main lessons that came out of this previous attempt to reformulate the policy. More specifically, it is an inconsistent position to say "homework is banned" and still keep a tag, or at least it is something that is very hard to write around. It will be easier now that the tag actually reads but the problem has by no means gone away. This is not to express (here and now) an opinion on whether we should change the policy or the usage of the tag. But a discussion of the role of the tag is integral in any attempt to reformulate the policy. One big reason for this is that the first encounter of most new users with the fact that not all homework questions are on-topic will be with the tag wiki excerpt that's shown when you try to tag something as homework. Another big reason is simply that the tag is an integral structural part of how we handle these questions. In particular, this discussion needs to include: • Do we want to change which questions are tagged as ? • Do we want to keep the tag at all? Do we want to burninate and black-list it? • What does the tag documentation - tag wiki and tag wiki excerpt - need to look like? I'm not putting forth any position on these issues at this time, but they do need to be on the agenda; if not, it will simply prove impossible (or at least very, very difficult) to write a consistent set of documentation for the new policy. • I actually think this would make a good separate question. And definitely one we should address before finalizing any new policy. – David Z Apr 7 '16 at 20:15 • I don't really have enough time and energy to initiate parts of this discussion. But I think this is a vital step 2b in your programme. – Emilio Pisanty Apr 7 '16 at 20:31 • We already discussed renaming the "homework" policy, and if we do get rid of the word "homework" in the close reason and help center (which I really think we should), we absolutely should nuke the tag as well. Whether or not a question is motivated by (or taken verbatim from) actual homework assignments is entirely irrelevant to whether or not a question is on topic. A question being homework is strongly correlated to it being a bad question, but the homeworkness of it is not the real issue. – DanielSank Apr 13 '16 at 8:05 • @Daniel To be honest, I feel the tag is working much better after the rename (but I've not been watching closely). It is certainly used by an important fraction of users to filter out exercise-type questions (e.g. this), so nuking the tag only makes sense if the new policy is very proactive against those questions. The point is that having a no-homework policy but keeping a homework tag is hard to write around because it is inconsistent; hence the role of the tag requires a thread of its own. – Emilio Pisanty Apr 13 '16 at 10:39 • Having just had a night's sleep, I realize my opinion as written last night is kind of stupid and I agree with @EmilioPisanty. In fact, the tag could still be useful. I reserve judgement pending a real discussion. – DanielSank Apr 13 '16 at 17:46 • @Daniel Hats off for that last comment =). – Emilio Pisanty Apr 13 '16 at 19:14 • @EmilioPisanty funny how perspectives change based on time of day and hours rested. – DanielSank Apr 13 '16 at 19:49 Relationship between velocity and position due to constant jerk proof check This question shows a detailed derivation, and then asks us to check whether the derivation is correct. It also asks whether there is a simpler derivation. Vote up if you think this should be on topic under the new policy, or vote down if you think it should be off topic under the new policy. • Maybe a "proof-verification" tag would be useful in case this kind of questions starts to be considered on topic – Javier Apr 22 '16 at 1:24 • I think the problem with such questions is that at the time of asking one does not yet know whether they will turn out to be interesting but in case they do it would be a valuable addition to the site. – caconyrn Apr 27 '16 at 12:40 • The reasons given for closing appear to be invalid : the question is very specifically focussed and shows obvious effort ("my attempt"). I think it reasonable of the questioner to doubt the correctness of his result (due to its ugliness) and to wonder if there is an easier method. I would feel the same. He is not merely asking "check my results." – sammy gerbil Apr 27 '16 at 18:47 • Seriously? This isn't even a physics question: it's pure calculus. – dmckee --- ex-moderator kitten Apr 27 '16 at 23:42 • @caconyrn We've talked about that before and the prevailing opinion is that we shouldn't need an answer to make a question on-topic. If the question cannot stand on its own, it cannot stand, even if great answers somehow prop it up later. – tpg2114 Apr 29 '16 at 20:00 • @dmckee Well Sir, you cant possibly truly understand physics without mathematics...."Seriously? This isnt even a physics question?".. Results of physics would not make sense is they do not follow Mathematical theories( Whats your take on uniqueness theorem in electrostatics?) – Prayas Agrawal May 15 '16 at 8:02 https://physics.stackexchange.com/questions/253477/specific-function-is-a-linear-combination-of-energy-eigenstates My lecturer made a statement: In the infinite square well potential$x\psi_n(x)$(where$\psi_n$is just the spatial part of an energy eigenstate) can be expressed as a linear combination of the energy eigenstates of the infinite square well, i.e.$x\psi_n(x) = \sum > c_m\psi_m(x)$. This came about by applying the position operator on an arbitrary wavefunction. I can't see how this function is a linear combination of the energy eigenstates. Thanks This is a purely conceptual question (one which does not fall under our current homework policy, for whatever that's worth) that nevertheless shows no effort on the part of the asker. Vote up if you think this should be on topic under the new policy, or vote down if you think it should be off topic under the new policy. Falling hailstones on windshield The question is well laid out, the set-piece components are clearly labelled, and the OP has clearly put in the work and isolated a specific question. However, it is still essentially a check-my-work question. Vote up if you think this should be on topic under the new policy, or vote down if you think it should be off topic under the new policy. Net acceleration of an object if too many forces are acting on it This questions has a concept in it but it is so simplistic/nonsensical that it should be closed. I don't find a descriptive "close" category for it. It's very clear what the question is, but the question is so simple as to be stupid. The OP obviously hasn't thought about the topic long enough before asking. Can we add another "reason" for closure to take care of thoughtless questions? Vote up if you think this should be on topic under the new policy, or vote down if you think it should be off topic under the new policy. • The judgement that the question is "stupid" and "nonsensical" is a relative one. The conceptual difficulty here is very basic, but it seems to be real for the OP. It is not fair to presume that she has not thought a lot about the question. It is not homework : it is clearly learning. I think the real issue here is : Do we want to allow such basic questions on PSE? Or do questions have to show a minimum level of understanding before they are accepted? I don't have a problem with this, but the threshold (A level? Degree?) needs to be made clear and be applied consistently. – sammy gerbil Apr 30 '16 at 12:14 • @sammygerbil Based on the response to another posting here "Speed of RF waves ..", responders don't believe that questions about very basic physics has a place. A statement about a threshhold level for questions would be a good idea. "If you don't understand what the terms position, velocity, and acceleration mean, don't ask." :) "If your question is about how to start working a basic instructional exercise, don't ask." I could repeat, for "what is a stupid question", the US Supreme Court justice when asked to define pornography: "I can't define it precisely, but I know it when I see it." – Bill N Apr 30 '16 at 16:58 • fwiw I downvoted this, but not because I think it needs to be addressed in the new policy. I would have closed this as "unclear what you're asking," which I interpret more broadly as "I can't understand why you have this question, nor what your internal thought process is." – user10851 May 18 '16 at 1:46 • @ChrisWhite That's exactly my point. "Unclear what you're asking" is used when the question is perfectly clear but doesn't need to be asked because the concept being asked about is basically a definition, e.g., "Is speed really distance divided by time?" If the question is truly unclear, that's one thing. If the question is trivial, that's not unclear. We should let the OP know it's a poor question because it is trivial, not because it's unclear. – Bill N May 19 '16 at 2:06 Quick question on rotational motion The question is based on a set piece and it starts off with it. The poster has some conceptual questions which are relatively well laid out. On the other hand, the question is rather straightforward and there's not that much to explain other than going through the procedure with the OP. Vote up if you think this should be on topic under the new policy, or vote down if you think it should be off topic under the new policy. • While not as bad as some of the other questions highlighted on this thread, the fact that it was 'answered' through a few hints in the comments makes it, to me, not a very good question. The hints did help the OP clarify the problem, but a solid answer to the question would seem, well, very 'solution-to-homework-assignment' in nature. I'm not sure what the benefit to the site or future visitors would really be. – Jon Custer May 3 '16 at 12:57 • (I'm personally not sure whether this should be closed or not. However, it's in the gray region where we should probably be concentrating on.) – Emilio Pisanty May 3 '16 at 13:34 • No doubt. An actual student (high school or university) would walk up to the teacher/TA and get the necessary hints in 30 seconds or so. But people turn to the internet rather than to others around them these days. Ultimately, it is unlikely that somebody in a similar conceptual situation would ever find this question though. – Jon Custer May 3 '16 at 14:14 Entropy of unattended music streaming and other useless processes (because you can never have too much data) Vote up if you think this should be on topic under the new policy, or vote down if you think it should be off topic under the new policy. • Voting up because I don't think this should be closed as homework. I think it's a bad question (i.e. downvotable) but I don't quite see why this is close-worthy. – Emilio Pisanty May 19 '16 at 10:26 • @EmilioPisanty This is about whether it should be closed under the new policy, which will have nothing to do with homework. This is a decent way to think about it: forget about the current rules on homework entirely. Do you think there should be a rule that would call for the closure of this question? Or not? (downvote/upvote respectively) – David Z May 19 '16 at 14:44 An apparent inconsistency in the form of Spin-z operator for spin 1/2 system This is a homework type question in that it is an exercise from Sakurai's QM book basically about forms of the zero and projection operators for hermitian operators. I think the close tag doesn't suit it: "Homework-like questions should ask about a specific physics concept and show some effort to work through the problem. We want our questions to be useful to the broader community, and to future users" It shows a lot of effort (most of the question is done and they even latex'd it in the link). As I've commented in the post that the close reason is essentially "punishing a user for doing more work than less work. One could've easily said 'I don't know what the operator in part b) is' and done nowhere near as much work as op. If op didn't have a mistake he/she wouldn't have asked the question!" Also in fairness Sakurai is a fairly well used book so in principle could be useful to future users. However it is essentially a where's my mistake type problem which isn't on topic, so I understand that, but I also don't agree with the reasoning "If you just need someone to check your work, you can always seek out a friend, classmate, or teacher" - here on meta which might for example punish a student that is self motivated to work over a summer break, where the teacher/lecturer is busy, and maybe other classmates/friends don't want to be doing physics over a break. Anyway: Vote up if you think this question should be on topic under the new policy, or vote down if you think it should be off topic under the new policy. • I posted my reasoning for adding this, as I'm not as high a rep user as others here, but if you would simply prefer an explanation of the problem and the link and the bold tagline, I apologise and will edit to remove my opinion! – snulty Aug 4 '16 at 16:50 • One point worth noting is that the OP did very little work in providing correct formatting for that post. They obviously LaTeX'd some stuff... and then refused to post the LaTeX? That's not winning any friends. That said, the way I see it this is nowhere near digested enough to be a useful question here. – Emilio Pisanty Aug 4 '16 at 17:18 • @EmilioPisanty I appreciate your comment, and I agree with the point about LaTeX! Digested in the sense that - it's not focused enough on the actual problem being asked? - I'm not sure I understand the use of the word. – snulty Aug 4 '16 at 17:33 • Digested in the sense that the OP should have done rather more work in pinpointing where the problem was before asking; as posed the question is not useful essentially for any future visitors at all. Ostensibly, the question is about part (c) of the problem, so it should have focused on that instead of making you trawl over parts (a) and (b), which then turn out to be wrong but only after much shuffling about, so the question suffers somewhat from the XY problem. Just not a useful question IMO. – Emilio Pisanty Aug 4 '16 at 17:42 • @EmilioPisanty That's actually a helpful link for me. I think I do agree with you, in it's form it isn't useful. I suppose the fact that it's on hold means it could still be refined to a decent question as per suggestion rather than being closed. Thanks for your comments! – snulty Aug 4 '16 at 17:46 • 'On hold' is operationally equivalent to 'closed', and questions on hold transition to 'closed' after five days. The terminology is chosen to emphasize that the question can still be reopened, but the fact is that all closed questions can be reopened if they're brought back into a useful shape (which then requires five reopen votes). In this case, the changes in the question put it in the reopen review queue and the result was to leave it closed. – Emilio Pisanty Aug 4 '16 at 17:52 • I made the same mistake as you, in thinking that if the topic is within mainstream physics then the question is de facto "asking about a specific physics concept." It took me 3 months to realise I had gotten this wrong. The question here is "where is my mistake?" which turned out to be "messing up the index in the expansion of the state vector" - an algebraic error, not a conceptual difficulty in physics, and not a useful lesson for anyone else. – sammy gerbil Aug 4 '16 at 20:31 • @sammygerbil I'm slowly starting to pick these things up about on/off topic. What I would like to believe though is that regardless of what one person gets out of a question, someone else can get something different from it. The op made an algebraic mistake but it brings an exercise to light that I hadn't done or looked at in Sakurai, so I got something out of it. Maybe someone in future might think it's a nice exercise and use it to set as a problem on a course. Who knows? Anyway, I'll accept policy if it's policy. I can see why people don't want every second question to be where's my mistake – snulty Aug 4 '16 at 20:39 Basic circuit problem The question poses a set piece, shows the OP's working, and asks us to explain what is wrong with their working. With a bit of work, it can be rephrased into something that's less dependent on the set piece and helping the OP understand how that circuit behaves as he's being told it behaves. It has an accepted answer which does a good job at addressing the conceptual difficulty at the heart of the question. However, even if fixed, it probably wouldn't be a great question. Vote up if you think this should be on topic under the new policy, or vote down if you think it should be off topic under the new policy. OP clearly isn't asking for help on the problem, they are asking what something in the question means. I think these types of questions are the similar enough to the types of problems that are supposed to be accepted under the policy that we should let them. Vote up if you think this should be on topic under the new policy, or vote down if you think it should be off topic under the new policy. • I would note that this doesn't show any effort. Granted, it's not a calculation-type question where the poster could be expected to work through some math, but I think a better question of this form would mention doing a web search or something. (Good example, BTW.) – David Z Apr 12 '16 at 10:37 • I agree as well, the lack of effort isn't great, but I think it's at least a starting point here. – Kyle Kanos Apr 12 '16 at 10:47 • Note that the question is deleted and thereby invisible for sub-I-don't-remember-the-required-reputation-but>10k-users (maybe for everyone?) – Martin Apr 13 '16 at 14:47 • @Martin: well that stinks. I'll try taking a screenshot later this evening for those who can't see it, thanks. – Kyle Kanos Apr 13 '16 at 14:50 • @Martin: Not for everyone. – user36790 Apr 14 '16 at 3:42 • This example was handled in the comments, which I think is OK. It was a basic misunderstanding brought on by the homonyms "break" and "brake", and not really about physics at all. A good time to help someone out without having to have a question and answer left cluttering up the site indefinitely. – dmckee --- ex-moderator kitten Apr 27 '16 at 23:56 • @dmckee : I agree. The OP is asking for help interpreting the question, not a conceptual difficulty. This is similar to DavidZ's example ("Does this length refer to length or wavelength?"). I think such questions can (and should) be answered by comments; they have no lasting value for the site and can be deleted after the OP has had time to read and possibly reply to the comments. – sammy gerbil Apr 30 '16 at 13:35 https://physics.stackexchange.com/q/250549 This question appears to be off-topic. The users who voted to close gave this specific reason: "Homework-like questions should ask about a specific physics concept and show some effort to work through the problem. We want our questions to be useful to the broader community, and to future users. See our meta site for more guidance on how to edit your question to make it better" – CuriousOne, John Rennie, AccidentalFourierTransform, MAFIA36790, ACuriousMind If this question can be reworded to fit the rules in the help center, please edit the question. Commentators viewed this question as a request for homework help, of the "check my work" variety. I think it asks more than that. I do not see why this question is judged to be off-topic. It asks about a specific physics concept (motion of centre of mass). The questioner demonstrates his attempt to solve it, but asks whether a simpler approach is possible. He prefaces the question : "I'm having a bit of trouble wrapping my head around this conceptually." Whether or not the problem has been set as homework is irrelevant in my opinion. The issue is whether it contains a conceptual difficulty, a discussion of which would be instructive to the broader community of users of this website. I think the answer to this question is a clear Yes. Vote up if you think this should be on topic under the new policy, or vote down if you think it should be off topic under the new policy • No reasons for down-voting? – sammy gerbil Apr 27 '16 at 19:03 • I agree with sammy. The OP asks questions about the quality of the question and about physics concepts related to the solution. OP doesn't ask for a solution, and does show effort. And his questions aren't stupid. – Bill N Apr 30 '16 at 4:49 • The means of discriminating homework-like versus conceptual questions has usual been treated as the difference between the asker focusing on a particular instance of a problem or asking about the concept in a more general sense. That one is clearly the former. And this is important lest adding the "concept" to a question act as a magic incantation to make it on topic. A lot of your evaluations here seem to be about whether answering the question would help the asker, but we're concerned about whether allowing the question would be good or bad for the site. Different question. – dmckee --- ex-moderator kitten Apr 30 '16 at 21:06 • @dmckee : Thanks for the feedback. I think I understand your distinction, but I question its reasonableness. It is much easier to discuss and clarify a concept in the context of a particular instance than in a more general sense. I agree that my example is the former (specific, focussed). The criterion of whether the answer will make the OP and other readers better physicists has been expressed by others in PSE Meta, eg John Rennie (I forget where). – sammy gerbil Apr 30 '16 at 23:54 • @sammygerbil I think you used the phrasing make them a better physicist as well in this thread on the harmonic oscillator answer :) – snulty Aug 4 '16 at 20:02 non constant acceleration problem The question probably arises from homework but the questioner has posted a detailed calculation, obtaining the correct answer after a "very nasty" integration. He then asks if there is a simpler method of arriving at the answer. Such a method is suggested by M.Enns and a detailed explanation posted as an answer by John Rennie. The solution is very instructive. I do not see why this is deemed to be 'off topic.' Vote up if you think this should be on topic under the new policy, or vote down if you think it should be off topic under the new policy • No reason for down-voting? How is this significantly different from the 'good homework' examples cited in @DavidZ 's post with 33 up-votes in meta.physics.stackexchange.com/questions/714/…? For example : physics.stackexchange.com/q/16182 – sammy gerbil Apr 29 '16 at 15:53 • We're talking here about what should or shouldn't be on topic under a new policy, not what is/is not on topic under an existing policy. So the downvotes mean that people don't want this question to be on-topic under the new policy. Doesn't matter if it is on topic under the old one. – tpg2114 Apr 29 '16 at 19:58 • @tpg2114 : Sorry, I don't see your point. I agree with your analysis of what these down-votes mean. I am suggesting that this question, which is currently deemed off-topic, should be on-topic under the new policy. And I am requesting reasons for disagreement with my analysis of the criteria. What features do they see which make it off-topic? I thought the point of DavidZ's request ("1. Collecting examples...") is to provide examples of what should be on/off topic. I am doing that. I think the fact that it is contentious is a very good reason for including it. – sammy gerbil Apr 29 '16 at 20:17 • You asked for reasons for the downvotes and asked how it is significantly different than the list on the other question to which you linked. I am saying that it doesn't matter if it is the same or different from the other question to which you linked because we're having a different conversation. The reason for the downvotes is because people don't want the question to be on-topic under the new policy. It doesn't matter how much it is like or unlike any other question in any other discussion. – tpg2114 Apr 29 '16 at 20:40 • @tpg2114 : Yes, I understand that the down-votes mean they don't want this question to be on-topic. I am asking why. The purpose of the discussion is surely to identify openly what criteria should be applied and what these criteria mean (how to interpret them). If the stated criteria seem to put a question on-topic but voters think it is off-topic, then how are they interpreting the criteria? I think this is a valid question within the discussion. As physicists, don't we expect to be challenged to give reasons for our views? – sammy gerbil Apr 29 '16 at 21:02 • I think we're just going to have to agree to disagree. I don't think the intention, right now, is to collect detailed opinions on why people vote the way they did. It is merely to build up a collection of questions so later we can sit down (most likely in a chat session where discussion is much more feasible than through comments on meta) and hash out how we can draw up a policy that encompasses all of the lines drawn from the collection of questions we have. I don't think we should be having discussions in the comments on every answer about why it is or is not on-topic. – tpg2114 Apr 29 '16 at 21:05 • This is a multi-part process and this is step one. If you want to use the argument that we are physicists -- we are collecting data right now and it's premature to analyze and discuss the results before they are even done being collected. Let's wait until all of the votes and examples are in, and then sit down and discuss what it means and why. – tpg2114 Apr 29 '16 at 21:07 • @tpg2114 : My purpose in asking for reasons is not to collect opinions but to challenge people to express openly how they are interpreting the criteria. It is pointless to formulate a policy unless it is clear what it means. If people (me, my down-voters) disagree on whether the criteria place a question on/off-topic, then there is a lack of clarity somewhere. I agree that it is unnecessary to examine every question : I also assert that it is pointless to examine questions which are not in dispute. An efficient process targets example questions where the issue is in dispute. – sammy gerbil Apr 29 '16 at 21:29 • – sammy gerbil Apr 29 '16 at 21:33 • What this question asks is "are there simpler ways to solve this?", which amounts to "Show me simpler ways to solve this". Granted, they provided a good and correct first effort, but regardless the question still boils down to something asking us to do the work for them (however redundant). I consider this just as off-topic as if no effort from the OP was provided. I only appreciate it more for the effort – Jim Jun 29 '16 at 14:27 • @Jim : You are being very unfair on the OP. It is a problem-solving question, which I now agree means it is off-topic. But asking if there is an easier way to solve a problem that you have correctly but laboriously solved is hardly equivalent to asking someone else to do your homework for you. Many on-topic questions show far less effort – eg How do we determine the location of particles?physics.stackexchange.com/q/265392 – sammy gerbil Jun 29 '16 at 21:41 • @sammygerbil I'm not being unfair, I'm just being cold-hearted. The resulting answers from this question would be virtually identical to the resulting answers from a question where no work had been shown. The only difference is that the correct method given wouldn't be part of any answer. As I said, I appreciate the effort shown and it does elevate the worthiness of the question in my eyes, but it is still fair to say that what they are asking of us is equivalent to a question with no shown work – Jim Jul 4 '16 at 12:34 • @Jim : I disagree. The fact that the OP has not been able to spot the method which JohnRennie used does not mean he has not made a reasonable effort. If you applied the same criterion to all questions then the only ones which would be answered are the ones in which the OP gives the 'correct' solution - and the only question which could be asked on PSE is 'Is this correct?' – sammy gerbil Jul 4 '16 at 12:44 • @sammygerbil I didn't say it was off-topic because he hadn't provided reasonable effort. In fact, I explicitly said the effort was very reasonable. What I said was that it was off-topic because it is effectively asking us to solve a problem for them. The fact that the problem was already solved by them is nice but not relevant. It is still the case that we are being asked to explicitly solve the problem, which is as off-topic as if no correct solution was ever given by the OP. NOT because the effort is insufficient, but because it is irrelevant. – Jim Jul 4 '16 at 12:48 • If all questions were held to that standard, the only ones to be answered would be that ones not asking us to show an explicit solution for a problem, which is perfectly fine with me. – Jim Jul 4 '16 at 12:49 For dry air cp/cv = 1.4, but for moist air it is smaller: cp/cv ~ 1.3. What is the reason for this difference? A fairly standard homework question that probes if you understand what the difference between heat capacity at constant volume vs pressure means. Seems black and white to me, but lets test the boundary. To me, the most likely issue for the poster is not unwrapping the ratio of the two to get back to the heat capacities proper. Vote up if you think this should be on topic under the new policy, or vote down if you think it should be off topic under the new policy. • I downvoted this answer because the linked question, whether homework or not, is a clear example of someone who hasn't done the least amount of "homework" (e.g., a simple google search). – David Hammen Apr 8 '16 at 18:55 • Since we are up/down voting the linked questions, this would be a good case for making answers community. – David Hammen Apr 8 '16 at 18:55 • @David No rep for votes on meta, so the only impact would be on users with very little meta activity who could conceivable come in for a post-ban on meta. – dmckee --- ex-moderator kitten Apr 18 '16 at 20:42 • The question appears to have been deleted now so I cannot comment. – sammy gerbil Apr 27 '16 at 19:35 • @sammygerbil - which would be another good indication that the community considered it homework-like! – Jon Custer Apr 27 '16 at 19:37 • @JonCuster : I don't understand how deletion works, but this sounds like saying that someone must be guilty of a crime because the police have arrested him. – sammy gerbil Apr 27 '16 at 22:19 How to calculate the electric energy caused by eletrostatic field stored in a region, given$V\$?

This question shows a good attempt at a solution, but it doesn't ask anything more specific than what the poster has done wrong (which makes it off topic under the current policy).

Vote up if you think this should be on topic under the new policy, or vote down if you think it should be off topic under the new policy.

• I think OP should get a comment on what's wrong in solution and then closed as off-topic. – Anubhav Goel Apr 11 '16 at 4:50
• @AnubhavGoel I'm strongly opposed to that. If the poster asks what they've done wrong, and we tell them what they've done wrong, we should do so as an answer, not as a comment. – David Z Apr 11 '16 at 9:42
• Then, we can answer it and then close it. – Anubhav Goel Apr 11 '16 at 10:50
• @AnubhavGoel That's no different. I'm strongly opposed to that as well. The entire point of closing a question is that it shouldn't be answered until it gets edited and improved. – David Z Apr 11 '16 at 11:10
• I am a little confused about why people want this to be off topic. Our proposal for the new policy focuses on outsourcing tedious calculations, and I find it difficult to see how this question is doing that. – David Z Apr 12 '16 at 6:09
• Clearly a "spot the (possible) error in my calculation" type of question. Better for the questioner to sleep on it and find his own mistake later (eg when his teacher marks it) than someone else spend time looking for an error which might not be there. It is doubtful that anyone other than the questioner can benefit from the answer. 'Off-topic' in my view. – sammy gerbil Apr 27 '16 at 19:21

On my opinion, every homework question should be offtopic. It is because science has very high ethical standards, and although it is only an enthusiast site, the spirit of these standards should be followed.

• Letting others solve our homework on the internet,
• Solving somebodys homework instead of him,
• And finally, giving the homework to a teacher and saying that it is my work,

...all of them are very strongly against the spirit of these standards.

I also think, answering a homework question should be also punishable.

Of course, the community can't examine if a question is really a homework question. Well-formulated questions, especially if the OP is capable to argument for that it is not a homework, could probably get their answers below the radar. It would also mean, the OP must consistently lie, cheat and commit plagiarism, but from our side it is impossible to decide about that. Anyways, considering the mean communication level of the homework OPs, if they are capable to credibly argument for that their question is not a homework, they are on a highly above the average level of the homework OPs.

Fortunately, in most cases, the OP is perfectly incapable even to use the formulas in his task. In very many cases they are even lazy to type in their question and they simply send scanned papers. And they do this from a very new account.

I think, in their case their accounts should be caged for some weeks - most high school homework questions have a much narrower deadline. And they should also get a moderator message about this policy, and that they will be welcomed after the weeks pass.

99% of them will then go away, and never come back. Actually, they will simply forgot even the existence of the physics SE in the moment, as they understand that the site won't help them in plagiarism.

The remaining 1% will be good members of the community.

• The goal of homework is not (should not be) to get good grades. It should be to create understanding. People who are too lazy to do their homework will hurt their own prospects of getting good at the subject at hand. Whether they "hand in as their own" is a further generalization that I cannot get behind. I contribute here to give people an opportunity to increase their understanding. What they do with my answers is not my concern. I agree about the "lazy" part of your post. If I sense people are not interested in my answer (except to get out of an assignment) I don't bother answering. – Floris Apr 18 '16 at 13:11
• I strongly disagree with peterh's view and agree with Floris. Whether it is homework or not is irrelevant : the issue is whether the questioner has a better understanding of physics because of the answer. Of course we should not do someone's homework for them : we should look for evidence that they are trying before we give help. We should encourage them to identify what causes confusion and address that, rather than do the particular calculation which is required of them. Although, providing the ultimate answer might be unavoidable. – sammy gerbil Apr 27 '16 at 19:30
• @sammygerbil I partially agree, I think such an answer is ok, which helps the OP to learn what (s)he had to. What is not okay: if (s)he instead of learning, simply copy-pastes the solution what (s)he found in the internet. I think, an answer to a homework should be made intentionally unusable for any un-ethical way. – peterh - Reinstate Monica Apr 27 '16 at 19:37
• @peterh : I agree with your motives, but I wonder if it is practical to try to make answers unusable for unethical uses (is it possible to check what use is being made?). I also doubt that freezing accounts will be either fair or effective, and it will require extra effort to allow for appeals. Like Floris, it is not my concern if someone copies my answer and presents it as his/her own. The best we can do, I think, is to avoid answering the 'homework' question itself and focus instead on the conceptual difficulty the questioner is having. – sammy gerbil Apr 27 '16 at 22:15

Does this length refer to wavelength or length? (as of revision 3)

This meets the conceptual question requirement of our current homework policy, but it seems not to show any effort. On the other hand, it's not clear to me what sort of effort we could expect to be shown for a question like this.

Vote up if you think this should be on topic under the new policy, or vote down if you think it should be off topic under the new policy

• I believe there is no physics concept here. As Kyle Kanos notes in his comment on the OP, it is a reading comprehension difficulty, not a physics difficulty. – Bill N Apr 6 '16 at 17:20
• @BillN sure. Just keep in mind that your vote on this (assuming you care to cast one) should reflect whether you'd like to see it made on topic under the new policy, which doesn't necessarily have to say anything about physics concepts. – David Z Apr 6 '16 at 17:33
• David thanks for the reminder. I don't think it's a proper question for PSE, and I've voted. I admit there are some (many?) improperly-worded problems in books that we could have a hand in clarifying for people, but there is no ambiguity in this problem. – Bill N Apr 6 '16 at 17:45
• I agree with @BillN : this is a badly worded problem, not suitable for PSE (because it benefits only the questioner). True, it is unambiguous to us, but the questioner is clearly confused and needs help understanding it. The effort spent in flagging it as 'off topic' is out of proportion to the response asked for. There ought to be a more efficient method of dealing with such questions : eg providing a swift response then auto-delete after 30 days? – sammy gerbil Apr 27 '16 at 20:41

Speed of RF waves and IR waves is same as 3*10^8 m/s

This seems to be a very elementary question with a straight-forward answer which can be found in every introductory physics text. I have not, however, been able to find this basic question on PSE with a straight-forward, well-reasoned, not-overly-complicated answer (or any answer for that matter).

Do we want a collection of elementary questions such as this, if they aren't duplicates, even if the answer is easily found in a text?

Vote up if you think this should be on topic under the new policy, or vote down if you think it should be off topic under the new policy.

• I would like to add that I generally consider "am I right?"-type questions to be dangerous (in terms of being close to off topic). – Danu Apr 7 '16 at 13:32
• I agree with @Danu's approach, with the qualification that the substance of the question is the important factor rather than the wording. (I disapprove Kyle Kanos' comment suggesting that the question be rephrased so that it meets the criteria, when it is not ambiguous : this is pedantic.) A good question might propose its own solution (which shows thinking) and is effectively asking "Am I right?" not in the sense of "Please check my calculation" but of "This is what I think but XYZ says otherwise - so who is correct?" – sammy gerbil Apr 27 '16 at 20:38
• I think the criteria should be : has the questioner thought about the question, and could he be expected to find an answer elsewhere? In this case I think he could. I suggest it should be dealt with the same as the "length vs wavelength" question. – sammy gerbil Apr 27 '16 at 20:39

Power dissipation in AC RC circuit

We should seriously consider not allowing such questions here. Under the current policy this is allowed homework, because the OP did a reasonable effort to solve the problem. I.m.o., however, we're better off forgetting about the whole homework issue and focus only on how interesting a question is from purely a physics point of view.

So, it can then be the case that a homework-like question is very interesting but it would not be allowed under the current policy because of lack of effort. On the other hand you can also have questions like this which are not all that interesting but because the poor student did go through all the trouble of working seriously on the problem, we're going to address it. It's better to not take such irrelevant issues into account.

Vote up if you think this should be on topic under the new policy, or vote down if you think it should be off topic under the new policy.

• "Under the current policy this is allowed homework, because the OP did a reasonable effort to solve the problem." I don't think that is what the current policy says. It's a pure "do my work for me" question. – dmckee --- ex-moderator kitten Apr 8 '16 at 3:15
• I like the approach of judging the question on its interest rather than rigidly applying criteria of effort and "check my answer". This question does raise some interest, judging by Farcher's comment. – sammy gerbil Apr 27 '16 at 21:03
• I voted (-1) because I agree that this should not be on topic. But I disagree intensely with "focus only on how interesting a question is from purely a physics point of view". If we allow close votes based on being "not interesting", we will end up with only questions that are of interest to the very small minority who regularly vote to close. We should strive for clear criteria that minimise judgement calls, and where the calls that do need to be made are not on the basis of personal taste. – Nathaniel May 6 '16 at 12:56
• @Nathaniel Yes, one has to put personal interest aside, this may not be easy to do. So, I guess we do need objective criteria, but these criteria should be chosen to so that they end up making that judgment. It's not all that different from a Referee having to judge if a paper is sufficiently interesting for the journal's readership. – Count Iblis May 6 '16 at 16:25
• @CountIblis no, it's completely different, because referees aren't self-selecting. – Nathaniel May 7 '16 at 0:09