I am wondering why this question was closed as homework.As OP said ,It was from an exam ,but I think it was not a homework type question.
3$\begingroup$ As JMac said "[...] I don't think it's really appropriate to answer this question given the person asking has not shown any personal effort or asked a conceptual question, as per the homework-type question policy". Also note that the OP didn't reply to either of the comments on the question. They just dumped their question & disappeared. $\endgroup$– PM 2RingApr 13, 2019 at 9:09
$\begingroup$ @PM2Ring It seems a conceptual question to me.there are a lot of questions which didn't show any personal efforts but they were not closed because they were asking about a concept.for example-physics.stackexchange.com/q/29082 $\endgroup$– user227513Apr 13, 2019 at 9:22
6$\begingroup$ The post was closed 2 years ago... is it really worth a meta post? $\endgroup$– user191954Apr 13, 2019 at 9:49
1$\begingroup$ It was flagged for closure before it received 5 VtCs and 0 leave-open votes in the queue. physics.stackexchange.com/review/close/174528 $\endgroup$– user191954Apr 13, 2019 at 9:53
1$\begingroup$ Besides just considering the differences in how well received the two different questions were ((+45/-0) on the time question and (+1/-4) on closed one)... The time question is asking about several concepts (which maybe you could argue is too broad; but that's a different question), the closed question is asking "Which one is easier? Are they the same?"; it could have been worded as a conceptual question maybe, but it wasn't as worded here. $\endgroup$– JMacApr 13, 2019 at 16:24
The question you've linked to, when boiled down to its essential structure, basically reads
I was faced with this set-piece exercise question, and I do not know the answer. Please tell me the answer.
It is smack in the middle of the class of questions that the homework policy deems off-topic. Note that the policy holds regardless of the origin of the set-piece, so "It was from an exam" is an irrelevant aspect.
That said, I do agree that this question did contain enough of a kernel of a conceptual problem that OP could have edited the question into an on-topic form which could have been reopened $-$ but the simple fact is that OP did not do this.
Note also that there are two aspects with respect to fixing closed questions: there's a difference between who can fix such questions, and who should do so. The onus falls on the asker, and nobody else is really obligated to fix such questions. However, anybody who cares enough can fix those questions, if the OP's intent is clear enough and the edits do not alter it (with somewhat more latitude with old, abandoned questions). If you really care about this, you're perfectly welcome to edit that question into a shape that's on-topic as per the homework policy, at which time it can be reopened.
1$\begingroup$ DavidZ actually had some examples of how this might be worded as a conceptual question on a tangentially related meta question here: physics.meta.stackexchange.com/a/9847/127931 $\endgroup$– JMacApr 14, 2019 at 15:18