A question's title is not meant to contain all the detail needed to make it answerable, only enough to give a rough idea what it's about. Area51 asks for titles and not bodies because it wants to focus on what kinds of questions should be on-topic; having a full body for each question would encourage people to waste time answering the questions instead of defining the scope of the proposed site.
What you're trying to type should be a question body, not a question title. A half-decent title for that question might be:
Determining the accuracy of g using a simple pendulum
That's enough for everyone to see what sort of question this is. The exact times and lengths have no bearing on whether this question is on-topic for your site, or whether the site itself is a good idea.
The phase where you can provide "complete" sample questions, with a title and body, is called "private beta".
Now, as for other users getting "confused," I have to respectfully disagree. The upvoted example questions you've posted are standard homework problems that would all be on-topic on other SE sites for that particular subject matter (given they met all the usual criteria of a good SE question rather than a lazy "do my homework for me" question).
The only example questions there that are actually unique to the "competitive exam" topic are the two highly downvoted ones about prep books and coaches for specific exams. I think the issue you should really be focusing on is how come the only two sample questions that are actually about exams are getting lots of down/closevotes? Allowing super-long question titles isn't going to change the fact that all the other questions are already covered by other SEs.
Though I can't speak for everyone voting on Area51, my guess would be that those two questions are likely either opinion polls, discussions, or off-site resource recommendations. StackExchanges have never been very good at providing those things. It's possible that the site you want to create is not and cannot be a StackExchange site.