RiNkY-

Stop thinking about the wheels. Imagine you're on a skateboard in an airport, and you're standing 20 feet from the end of one of those people-mover conveyor belts (on the side where people step off, not where you get on), but there's no people on it. Imagine that you have a jetpack attached to your back and that somehow you're able to control the jetpack so you don't kill yourself.

How do you start moving? You fire up the jetpack, right? How did you start moving? The jetpack pushed against the air.

OK, now you're moving forward because the jetpack is pushing the air, and you now jump onto the conveyor (which is moving backwards). Your roller skate wheels suddenly start spinning faster. What happens to the air that the jetpack is pushing against? Did it suddenly become very windy? No? Then you continue to move along the conveyor, although opposite to its direction of travel.