# Why is this not focussed enough?

My question here has been closed as "not focussed enough".

Given I got exactly the answer I wanted in next to no time, I find that hard to believe. Especially considering how concise and to the point the answer is.

How exactly is it not focussed enough?

• This is unrelated to whether your four questions and eight examples made the post unfocused… Did you read Wikipedia before asking here? We have a “do a little research before asking” rule so that PSE members don’t waste time repeating what can be found in standard references. (If you were’t aware that the operator is called “Del”, the article on vector calculus, a term you knew, would have told you that.) Also, this question is really about math, not physics. So I think your question had multiple issues. Feb 19 at 7:59
• I had googled it... Which is how I got as far as I did... What was confusing me was that what was in the slides didn't exactly line up with what was showing up on google. Hey ho... I'm not going to argue, I got the answer I needed Feb 19 at 17:55
• The error in the slides regarding convective acceleration means that the video lecturer doesn’t understand the subject well enough to be lecturing anyone. The answer you accepted did not discuss $(\vec v\cdot\nabla)\vec v$, although its meaning can be determined using the definition of $\nabla$ given in the answer. I think you got the most important correction from a comment by Sebastian Riese. Feb 19 at 18:27
• So because you asked four questions and the answer answered only three of them, the worst mistake in your slides never got corrected by an answer, and some readers in the future are likely be left confused. This is one reason that multiple questions are bad. It is unfortunate that a partial answer was posted before your question was closed. Feb 19 at 18:39
• @Ghoster we have dozens of questions on $\left(\mathbf{v}\cdot\nabla\right)\mathbf{u}$. Linking any one of them would have sufficed (but not needed anymore since I've taken the liberty) Feb 20 at 3:35
• @Ghoster - Thanks for explaining, I think I somewhat get your point now. However, I'd still argue that I found the answer useful, which means other people likely will to. So that's still better than there not being an answer. Let's not let perfect be the enemy of the good. It seems your issue would be better addressed by editing the answer to add the missing piece than by closing the question no? Feb 20 at 12:11
• I’ve addressed the issue by commenting on the answer. I don’t edit deficient questions or answers; I only fix typos, MathJax, and other superficial things. I believe that the writer is responsible for the essence. Feb 20 at 18:11
• @Ghoster - Can I ask why? That's a rather strange position to take if you ask me Feb 20 at 18:14
• Personal responsibility. If my comments are not enough to help them improve what they wrote, that’s their issue. Feb 20 at 18:15
• Fair enough, I guess? Although that feels somewhat anathema to the community approach to these things the site tends to take. At the end of the day the point isn't for an answerer to show off, it's to collect good answers for everyone to benefit Feb 20 at 18:17
• I edit Wikipedia in substantive ways; the difference is that it doesn’t attribute articles. I don’t care for my work to appear to be someone else’s. I could of course have written my own answer, but I felt that your question didn’t show sufficient prior research. In general, I tend to answer only questions that I find interesting. Feb 20 at 18:26

I did not vote to close, but if you see the reasoning behind a question being closed for "not being focussed enough", you'll find the following text:

Needs more focus - If your question has many valid answers (but no way to determine which, if any, are correct), then it probably needs to be more focused to be successful in our format.

This question currently includes multiple questions in one. It should focus on one problem only.

This can often be fixed by breaking the post into multiple questions, or by focusing on a specific part of the problem.

Your question did indeed include multiple questions in one. Each of the 4 points you listed could have been addressed by user in an answer, therefore resulting in multiple answers partially addressing your whole post.

While you got an answer that satisfied your question, it is worth to point out that said answer may be considered far from exhaustive given the many example equations you had listed in your post. The answered just wrote the definitions of the symbols (except the $$\cdot \nabla$$ one that you also asked about, though it was addressed in a comment), but another answerer may have well given you explanations using the written out $$\nabla$$ in the context of hydrodynamics.

If all you wanted were the definitions of the symbols, you could have avoided the list of many equations (and slides) of hydrodynamics which may have led readers away from your main question, that was about the mathematical definitions of the symbols.

This is my interpretation as to why the question was closed for "needing more focus".

• Well the context is important as symbols have different meanings in different contexts. I'd have also thought a question per operator would've been a bit ridiculous... Feb 19 at 5:29