Stupid Questions

I have never understood why there is such a term as a 'Stupid Question'. Through my entire life I have been accused of asking stupid questions, but surly it is only stupid people who don't ask questions!?

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The answer to a lot of those questions are mostly straight-forward, but what about something more meaty from Professor Walter Lewin at MIT:



The question posed above is very generalised, but does that make it a more or less of an intelligent question?
Anyway see Kelvin's Thunderstorm for the answer.