Please stop downvoting higherpurpose for being curious and asking a question like this. We all lack knowledge in different areas, that shouldn't prevent us from positively participating because we fear repercussions.
I would rather see that people are prevented from participating when they have nothing very insightful to say. This policy prevented me from posting some stupid comments and I think this made HN better. You should stop and think before submitting your comment. Otherwise HN will change into another slashdot where stupid uninformed comments are rampant. If there are no repercussions to people who don't think before posting, there will be more people, who don't think before posting ;).
You're right, stopping and thinking before posting is important. (You can also think after posting, and edit!) We want reflective comments and votes as opposed to reflexive ones. But we also want HN to be a place where people are welcome to ask simple questions.
There are many reasons for this. Not everybody knows the same things. It can be surprisingly valuable to go over the basics even when you already know them. And then there's the "stupid question" that so often is far from stupid—often everyone else in the room is wondering the same thing. It usually isn't obvious in advance whether a question is deep or shallow.
Asking simple foundational questions out of interest isn't a problem around here. The finest conversations always welcome them. It's the intellectually petty discussions, where people try to one-up each other with displays of knowledge, that can't handle them.
A question was asked. That implies a lack of knowledge. Given that lack of knowledge, how is one to know if the question is regarded by people who do have that knowledge as "stupid"?
I wouldn't downvote it, but "Is this also the first real perpetual motion machine?" indicates that the one asking the question is familiar with the terminology, and even knows that all known perpetual motion machines aren't real. If so, in this forum, I think we can assume that (s)he also can google that term and make some deductions from what (s)he finds. It is not as if (s)he does not have Internet access.
"I googled, and found differing opinions on whether perpetual motion is possible. Is this an example that shows that it is?" would be a better question. It still would surprise me that there are people on HN who would pose such a question about such a simple device, but it would show some intelligence and a will to make an effort to learn. The OP still may have both, but the way the question is posed doesn't show it.
Sure, I can induce that if it is a battery, it is being used as a power source. Others may induce that it is simply a thing with north and south magnetic poles. While I understand I am contributing to the phenomenon, HN threads often derail and become critiques about what HN should and should not be.
