When you place some rails on this position and launch a rail,(see Image, only two off them are important), the minecart appear like he is on a rising rails. It can be seen by pushing the minecart when he is on the top rail.(it's very quick)
On the picture, the minecraft has fall, and then stoped on this position, but i wasn't able to make a non moving minecart like this again (it may be hard). But it can always be seen when the minecart is moving between the two rails.