Last week's question: What would a transportation system look like if the ground is frictionless?
I have several ideas. There are several transportation systems already in place for traversing a frictionless medium, although not on the ground. Hot air ballons don't rely on ground friction, nor do gliders and blimps. Gladers move by wind, which will work equally well on the ground (land sailing). Blimps and planes, on the other hand, push air away from it for propulsion. Propellers and get engines would therefore to do the same on the ground.
Other ideas I had involve some initial energy. If the distance to be traversed is not too great, then air resistance is negligible. I can imagine nets being spread around an area, and people would just push off to be caught in a net at their destination. Setting up the net initially would probably require a tether, like how astronauts do space walks - which, by the way, is truly a frictionless environment.
On a more science fiction note, it may be possible to do something with eletro-magnets. It will basically be the principle in maglev trains. I can imagine some sort of remote, a magnetic suit, and a magnetized floor. Using the remote will activiate electro-magnets, which will push and pull you in one direction, or alternately slow and stop you.
Considering I just came back from broomball, some of these things sound really exciting to try out.
This week's question: Humans are often fearful of abstract ideas. Job interviews, asking someone out... these things have no immediate physical danger to us. So the question is, do animals have similar kinds of fears, and if so, from what?