How does the plane lift without getting to its takeoff speed? That is the whole question... DOES the plane get to its takeoff speed?Why will the wheels and conveyor move at infinite speed? Once the areoplane has lifted there is no longer contact.
The wheels still do not provide propulsion …How does the plane lift without getting to its takeoff speed?
incorrect assumption
It's not an incorrect assumption any more than an assumption that it's referring to the forward speed. If you put a car on blocks, put it in gear and put your foot on the throttle you will get an indicated speed of say 50mph. Because the car isn't going forward does that mean the wheel rotational (Or circumference speed more precisely) speed of the wheel is zero? Of course not.I can see where you are coming from. 99% of people would read it as the wheel surface speed. The possible confusion would be about the MOVEMENT of the wheel as a whole (ie the plane speed), not the surface speed.
Rotational speed is an incorrect assumption because revolutions or angular speed cannot equal surface speed, it's a non starter.
Imagine a 747 is sitting on a conveyor belt, as wide and long as a runway. The conveyor belt is designed to exactly match the rotating surface speed of the wheels, moving in the opposite direction.It's not an incorrect assumption any more than an assumption that it's referring to the forward speed. If you put a car on blocks, put it in gear and put your foot on the throttle you will get an indicated speed of say 50mph. Because the car isn't going forward does that mean the wheel rotational (Or circumference speed more precisely) speed of the wheel is zero? Of course not.
So they would be stationary thenImagine a 747 is sitting on a conveyor belt, as wide and long as a runway. The conveyor belt is designed to exactly match the rotating surface speed of the wheels, moving in the opposite direction.
Does that make things any clearer? that is how it should be read from my point of view.
As Pete says, the whole question leads to incorrect assumptions regardless of wording![]()
Actually i see your point now, clever clogsSo they would be stationary then![]()
This is elementary.The wheels still do not provide propulsion …
No - the plane moves forwards in the air - the bottom of the wheels (in contact with the conveyor) rotate rearwards. The conveyor has to move forwards (as that is opposite to rearward) at the same speed as the wheels - so they would stay stationary.No! The wheels would only be stationary if the conveyor went the same way as the wheels.
You're going off the top surface direction of the wheels, not the bottom surface in contact with the conveyor. Why you are choosing to do this, i don't know. It's obvious that you use the surface in contact with the conveyor
Actually i see your point now, clever clogsIt's an assumption which had never occurred to me.
If you totally ignore the wheels and conveyor, of course the plane is propelled forward. The trick in the question is in the fact that the entire scenario as a whole including the wheels/conveyor is impossible.See my previous post.
Sorry mate i see your point, I edited my postNo - the plane moves forwards in the air - the bottom of the wheels (in contact with the conveyor) rotate rearwards. The conveyor has to move forwards (as that is opposite to rearward) at the same speed as the wheels - so they would stay stationary.
The top of the wheel rotate in a forward direction when the plane is going forward.
You can tie yourself up in knots all day thinking about thisActually i see your point now, clever clogsIt's an assumption which had never occurred to me. Whether you choose to go off the top dead centre of the wheel surface going forwards, or the bottom dead centre which is going backwards.
The person who came up with this question was either an evil genius, or just as simple as the rest of us and didn't realise how open to interpretation is isYou can tie yourself up in knots all day thinking about thisAnd I still don’t know that I’m right, just that I “think” what I’m saying makes sense to me (at least!!)
Whoever came up with it wasn't asking you to design the system to do it, just what would happen if you could. And that answer is easy. You're in for some time of the flippin kid behind twatting the back of your seat . . .The person who came up with this question was either an evil genius, or just as simple as the rest of us and didn't realise how open to interpretation is is![]()
Well yes, of course, hence hiding behind the sofa!I must look and see the speedometer the next time I pilot a Jumbo. Surely they use speed sensors not speedometers.