J. Michael Straczynski (JMS) is a pretty spiffy SFTV writer. He usually gets things right, but basic physics and math have never been a strong suit—a weakness he readily admits. This lead to an interesting situation when, even in the face of overwhelming evidence, his asserted that Starfuries spiraled out of their launch bays. It caused quite a stir on the B5 newsgroup. Dozens of fans came forth with some very well written posts explaining the concept, but JMS just couldn’t wrap his head around it.
If you swing something in a circle then release it midspin, it will keep going in a straight line until some other force acts upon it. A straight line, not a curve. The only time anything curves in motion is when there’s a force acting upon it like gravity or wind. It’s often hard for people to intuitively grasp this until they’ve seen it themselves. The usual reason most people believe it curves is their experience with swinging things on the end of a rope. When most people let go of a swinging rope, they let the rope drag through their hand which in turn becomes a drag on the object at the end of the rope.
[2003-Feb-17] Jeff Meyer suggested the Olympic hammer throw as another example to help people understand this:
The athlete spins in a circle swinging the object, then he/she releases it and it travels in a straight line. Anyone familiar with the event should then be able visualize it, and anyone unfamiliar would at least have something to reference in order to better understand it.