Posted by Bartholomew (18.104.22.168) on March 20, 2003 at 15:42:03:
In Reply to: how does... posted by pork (22.214.171.124) on March 20, 2003 at 14:20:06:
> > How much does fluttering accomplish if the bird is weightless?
> your bird ghost get around? Is it trying vainly to propel itself on the terms of the physical plane when it has crossed over to your imagined spiritual plane? Is it "stuck"?
> I considered the weightless/fluttering conflict at first, but it seemed ambiguous, and I'll admit, at the risk of sounding daft, that I wasn't completely sure. Physics is not my strongest suit.
> I considered, also, that the closest tangible equivalent to this scenario would be a bird floating motionless in deep space, trapped in a bauble of air. It wouldn't be weightless in the absolute sense, but its weight would be reduced beyond the point of ordinary detectability. Aren't things propelled more easily as their weight decreases? What would happen, theoretically, if the property of weight were actually removed completely? Would the bird even be capable of fluttering? Take my dumb questions in stride, please, and enlighten me.
You're partially confusing it with "mass," which is how hard it is to start the object moving. Weight is the force that gravity exerts on the object.
Indeed, way out in outer space would be about the only place you would find a weightless (approximately) bird. This is another clue.
There have been no adult birds taken into orbit, so we don't know exactly how well they function when gravity is irrelevant. However, considering that "fluttering" wing strokes are designed to produce lift and speed at the same time, a weightless fluttering bird would probably just move backwards in a circle.
Post a Followup