The conveyor belt thread.

[BigJoe#1]

Not really. It's a pretty counter-intuitive and often badly-worded puzzle.

This is the question asked: "If a plane was travelling down a giant conveyor belt at 180mph, trying to take off, but the conveyor belt was travelling at 180 mph in the opposite direction, would it be able to?

You would still have the thrust of the jet engines at the back."

IMO, the question is pretty straightforward. The jet engine/propeller provides the forward movement by pulling against the air - what happens on the ground is irrelevant if the wheels are free to rotate.

Traction?

But the plane is going backwards on the CB. To stay still and enable you to step off the Plan (should that be what you wish to do), it needs to travel at 180mph, from this position it then needs to accelerate a further 180mph.

As for wind speed and lift, unless the plane can fly going backwards ailerons and all, the argument is invalid!

 

[blumoon]

This would happen

[youtube]http://www.youtube.com/watch?v=bnBr3enzW1I[/youtube]

 

[steviemc]

Tried it with a fox...epic fail!

 

[blueish swede]

Shouldn't the question be

"If a plane was travelling down a giant conveyor belt at 180mph, trying to take off, but the conveyor belt was travelling at 180 mph in the opposite direction, would Stoke fans still point at it?"

 

[yerwot?]

the plane is using just enough power to overcome the friction in the wheel bearings, not enough it goes backwards, too much and it travels forward in relation to the air and the ground.
How would it become airborne, as control surfaces have no effect in still air? (ignore prop-blast). The GPS, and air speed indicator would show a static state.
Once(if) the wheels rise, all that is left is an airframe with no means of support unless it is over-powered to an unheard of degree.
The conveyor belt is a smoke-screen, it has no capacity to provide lift, move air, or affect anything but the wheels. Exactly the same effect could be achieved by attaching a cable to the back of the plane to achieve the same effect. I.e. a static plane. Firmly on terra firma.

 

[Plays By Sense Of Smell]

Put simply, if it could take off, then I'm pretty sure the world's airports would have all invested in conveyor belt runways by now saving themselves tons of real estate costs in addition to the bottom falling out of the global helicopter market.

But would they be cheaper than a steam catapult?

 

[117 M34]

I'm going for no based on the forces being Balanced so the plane won't move

 

[whp.blue]

The plane would definitely take off as the thrust forward comes from the engines and not from the wheels. The engines and wings are travelling at 180mph (or whatever) which enables take off.

All that the conveyor belt does is increase the speed of the wheels going around so that as the plane reaches 180mph the wheels are doing 360mph.

The plane does not rely on the wheels for forward thrust so therefore takes off

I agree with this for what it is worth

 

[Blue Mist]

How can it be stationary if it's travelling at 180mph? Either it's travelling, or it's stationary.

If it were a paper aeroplane, it'd definitely be stationery.






Coat's on, already.

Put your coat back on the hook and make your way to the dressing rom, your here all week.

 

[Ourman]

[video]http://www.youtube.com/watch?v=YORCk1BN7QY[/video]