I recently answered -How much forward force is exerted by an idling automatic car- but it was closed as too broad. I dont particularly care either way, and I respect the moderators judgment, but its closure confused me.
I understand it is a general question, broad because it does not specify the type of car, engine, transmission, etc. required to arrive at a precise value. But, in my opinion, lack of specificity does not invalidate the intent of the physical question asked. It is possible to demonstrate the physics involved; applying reasonable assumptions, a useful answer is possible. Even fully specified, an exact answer is not possible (without extensive experimental data) or required to provide a useful answer.
There are many broad, useful questions without exact answers.
For example - Is it (practically) possible for a large building to be a Faraday cage?: Dimensions, materials, and signal strengths are not specified (needed to determine the effective strength). The physical concept is discussed in relative terms, yet this is undoubtedly a useful answer.
Physical concepts and practical assumptions often provide useful answers to questions that lack specificity. Unless explicitly stated, we assume collisions act on the centers of mass, etc. Concepts and approximations are often more useful than mathematical proofs. How are these factors considered?
When are questions considered broad enough to be closed?