Ok, on the water question:
If my understanding is correct, then when you put something in something else such as a boat, then it doesnt push down and displace as much as it would out of the boat and just in the water. So basically, I think the water would rise, as the
iron would probably while in the boat not be totally submurged, and would probably not displace as much as it would if it was submerged. Of course all of that would depend on various things like whether the water had anything like salt in it, making it more boyannt and the shape and make-up of the boat.
On the Boeing question:
If the wheels are rolling exactly in sync, does that mean the wheels on the belt are also rolling forwards, in which case, the Boeing, would probably
take off twice as easy as it would be going at its own full speed as well as the full speed of the rubber belt, thus doubling the planes speed; kind of like one of those
flat escalator things they have at airports, where you can stand on it and go at a set speed, or you can walk, whilst standing on it and go at about double your normal walking speed. Of course as soon as it leaves the
ground, it could come into problems, because of the way its speed would be almost cut by half... but thats another matter.
Diarmuid