Quote:
Originally posted by Mobycat:
The plane has to gain airspeed to lift off. The force of gravity keeps it on the ground when it's stationary.
Correct. Gravity also keeps the plane on the ground when it's moving. If it's moving at a great enough speed, gravity is counter-acted by aerodynamic lift.
Quote:
Originally posted by Mobycat:
For it to move forward, it would have groundspeed. The air is calm. That means the air is equal to the ground in relation to the plane. If the plane cannot move on the ground, it cannot move in the air.
It means the air is stationary, even if the conveyor moves under it. Here you are assuming that the aircraft cannot move on the ground.
Quote:
Originally posted by Mobycat:
It cannot move on the ground, because the conveyor is negating it's forward movement.
Incorrect. The conveyor cannot exert enough force or friction on the tires to counteract the thrust of a jet or prop.
Quote:
Originally posted by Mobycat:
It wouldn't matter if the wheels had a true no-friction connection to the plane. The conveyor is STILL going to counteract it.
The very purpose of the wheels is to reduce friction with the ground (conveyor, in this case). The purpose of the prop/jet is to create friction with the air. The props/jets create immense power and lots of friction with the air, creating forward movement. The wheels make it easier to move the aircraft over the surface. The surface moves in the opposite direction of the plane, with the conveyor, at twice the normal rate.
Quote:
Originally posted by Mobycat:
It WOULD matter if the wheels were locked - the jets should have enough thrust to burn the wheels off (since the conveyor then wouldn't move, since the wheels aren't moving).
The wheels being locked matters in another way-it is creating more friction with the conveyor/ground. This friction can still be overcome, though it is not safe. An aircraft under full power with brakes locked will move forward.
Quote:
Originally posted by Mobycat:
The wheels move because of the jets. Which means the jets in effect move the conveyor (since it matches the speed in opposite).
The jets do not move the wheels. The jets push the plane, and the friction with the ground causes the wheels to move. The original problem says nothing about the wheels pushing the conveyor, it says the conveyor matches the plane's speed.