Time for a sum-up

[cultureofdoubt]

So, I'm a bit surprised the plane brought out all that discussion when the freaky backwards-in-time antics of photons didn't (although that's perhaps a bit more heavy going to decipher unless you're familiar with Young's slits).

Comments

[azureskies]

Depending on the version of the question you read the conveyor belt moves back at either the speed the plane moves forwards, or such that the plane remains motionless.

I genuinely don't understand the difference here. If the conveyor belt is moving at the speed that the plane WOULD BE moving at on fixed ground, then surely the two relative speeds cancel each other out and the plane is motionless?

[cultureofdoubt]

No, in the first case the wheels can do whatever they like without affecting the motion of the plane, so the plane can go forwards while the belt goes backwards, and the wheels whizz away as necessary.

In the second case the belt moves back fast enough that whatever friction is in the wheel system gives a force to the plane to keep it in the same position.

[beingjdc]

The reason I didn't buy this concept is that for the plane to take off, the relative motion of the plane to the ground on which it stands is faster than the relative motion of the belt to the ground on which it stands, so I would argue that the plane is in fact not moving forwards at the same speed as the conveyor belt is moving backwards.

[cultureofdoubt]

With frictionless wheels the belt is free to move as it pleases though.

[chrisvenus]

As I vaguely implied in my comment on the other post I missed the reading that the plane was decoupled from its conveyor belt. I assumed that as with all these kinds of question the plane was effectively stationary and it was all aimed at whether its the planes speed relative to ground or the air that is important.

Also if the wings are spherical then I say it won't take off. :)

[cultureofdoubt]

Yeah, it's kind of ambiguous that way too.