A Riddle

Chris · 12-19-2006, 09:03 AM

Ok, here's a riddle for you...

You have a 747 sitting on a huge conveyor belt. This conveyor belt is controlled by a computer that precisely matches the speed of the conveyor to the speed of the jet, only going the opposite direction. When they throttle up, will the jet be able to take off?

ridgewalker243 · 12-19-2006, 09:11 AM

oops almost blew it

12-19-2006, 10:50 AM

I said yes, but like I always say "what the heck do I know

".

Dredly · 12-19-2006, 11:21 AM

Quote:

Originally Posted by Chris

Ok, here's a riddle for you...

You have a 747 sitting on a huge conveyor belt. This conveyor belt is controlled by a computer that precisely matches the speed of the conveyor to the speed of the jet, only going the opposite direction. When they throttle up, will the jet be able to take off?

I say No, because the lift that the plane needs is gotten by air passing over and under the wings. Without forward progress the plane will not get the air required to give it lift... then again I could be completely off

BUNNYMAN · 12-19-2006, 11:27 AM

I refuse to answer......

or all of the above....

neither of the above....

why do we park in a driveway and drive on a parkway.......

Dredly · 12-19-2006, 11:37 AM

Quote:

Originally Posted by BOWMAN

I refuse to answer......

or all of the above....

neither of the above....

why do we park in a driveway and drive on a parkway.......

Drive on a parkway? I think that depends on which parkway your reffering to

Sportsman · 12-19-2006, 11:53 AM

Just spinning the wheels

CSS Shooter · 12-19-2006, 12:07 PM

If they have the belt set to match the speed of the Jet the forces/speed will be equal and not allow forward motion. If the jet is moving left to right and the belt is moving right to left then the force/speed is equal. Unless I am having a brain Cramp which is possible. The wheels should not be moving. So like Dreadly said there will not be any uplift from air flow.

12-19-2006, 12:43 PM

the reason I said yes is because the engines are pushing the body of the plane and not driving the wheels like on a car, so in my figuring the plane should still be able to move foward. But then again like I said before, "what the heck do I know".

How long do we have to wait for the correct answer????

Jay Are · 12-19-2006, 01:27 PM

I would say No..

I believe the plane relies on air to lift it off the ground. With the conveyor going the opposite way it won't create the wind resistance needed to lift the wings of the Jet.

BUNNYMAN · 12-19-2006, 02:31 PM

Quote:

Originally Posted by CSS Shooter

If they have the belt set to match the speed of the Jet the forces/speed will be equal and not allow forward motion. If the jet is moving left to right and the belt is moving right to left then the force/speed is equal. Unless I am having a brain Cramp which is possible. The wheels should not be moving. So like Dreadly said there will not be any uplift from air flow.

not moving yes......but they are spinning.....

Ronhop · 12-19-2006, 05:57 PM

No airflow no lift. Having said that we need to thing about this a little more carefully.

The thrust from the engines have nothing to do with conveyor belt. If it were a car, for example, the car would not move. If the airplane's wheels were driven then the airplane would have an issue for sure. We don't know if the airplane was moving forward and if so what the airspeed was and what airspeed would be required to allow the wings to provide the necessary lift to raise the aircraft from the ground.

Speed of the conveyor vs. the speed of the jet...

I am changing my vote to "We don't have enought information to answer yes or no"....

Ron

12-19-2006, 06:15 PM

Quote:

Originally Posted by Chris

Ok, here's a riddle for you...

You have a 747 sitting on a huge conveyor belt. This conveyor belt is controlled by a computer that precisely matches the speed of the conveyor to the speed of the jet, only going the opposite direction. When they throttle up, will the jet be able to take off?

if you read the riddle it says the conveyor belt is going to spin at the same speed the plane is moving, not at the speed the planes wheels are spinning. Riddles usually are in tended to throw you off. The only thing the conveyor belt is going to do is make the tires spin at twice the speed that it normaly would. The plane would continue as it would on any run way, just the tires speed would be affected, so if the plane is moving then the plane will have lift which will get it off the ground.

BUNNYMAN · 12-19-2006, 07:04 PM

you all are reading too much into this one I think.....

12-19-2006, 08:08 PM

Quote:

Originally Posted by BOWMAN

you all are reading too much into this one I think.....

isn't that what riddles are all about??

bullspotter · 12-19-2006, 09:08 PM

I think its going to push the conveyor so fast that it will catch on fire, then it will not work, but the plane will be close to taking off, but they used up to much of the runway, trying to keep it on the stupid conveyor, then a big gust of wind will come up and blow the plane over sideways causing a wing to hit the ground, wich causes the plane to skid out of controll sideways into the west end of the airport, wich was thankfully not in use due to construction..... Thats what i think will happen!!!!

Then the new riddle is how long dose it take to fix the airport?

bullspotter · 12-19-2006, 09:14 PM

O i also voted yes it will take off, moving air makes planes fly not wheels turning, you hold a 747 wide open throtle..... uhhh it pry will move.... Thats my guess any ways... so chris, when you going to reveil the proper awnser here....... some of us might loose sleep!!!!

12-19-2006, 09:20 PM

Quote:

Originally Posted by bullspotter

I think its going to push the conveyor so fast that it will catch on fire, then it will not work, but the plane will be close to taking off, but they used up to much of the runway, trying to keep it on the stupid conveyor, then a big gust of wind will come up and blow the plane over sideways causing a wing to hit the ground, wich causes the plane to skid out of controll sideways into the west end of the airport, wich was thankfully not in use due to construction..... Thats what i think will happen!!!!

And I thought I was reading to much in to this riddle

BUNNYMAN · 12-19-2006, 09:37 PM

Quote:

Originally Posted by dodgensince74

And I thought I was reading to much in to this riddle

yeah sometimes he is an overreading overacheiver........

bullspotter · 12-19-2006, 10:22 PM

na i cant read relly well good or spelll veyr good, but i am a overreacheirver....... hehe just like someone else on here who needs a

......

longcut36 · 12-21-2006, 11:07 AM

can I change my vote to, maybe it will, maybe it wont.

Dredly · 12-21-2006, 02:23 PM

If the plane doesn't move then it won't create any lift.

hoyt_hunter007 · 12-21-2006, 08:33 PM

from what i understood in physics class (very little), there's no way the plane can take off, the plane will have no net movement in the forward direction. with no forward movement, it cant get any air to run over the surface of the wing to create lift. the wheels have nothing to do with the flight, if the plane itself isnt moving, it cant fly...i could be wrong, but this is how i look at it...

bullspotter · 12-22-2006, 12:32 AM

the plane is not driven by the wheels.... its driven by air movement by the engines.... the air WILL push the plane forward, it will move forward no matter what the wheels do!! I say it will take off.... Dosent matter whats going on with the wheels....

BUNNYMAN · 12-22-2006, 02:57 PM

Quote:

Originally Posted by bullspotter

the plane is not driven by the wheels.... its driven by air movement by the engines.... the air WILL push the plane forward, it will move forward no matter what the wheels do!! I say it will take off.... Dosent matter whats going on with the wheels....

if the wheels are not free spinning then the plane will fall off the back of the conveyer....SO IT DOES matter what the wheels are doing....the wheels may not be what drives the plane foward but if they are not spinning then it is like the breaks are on.......

olman · 12-22-2006, 05:51 PM

Invision this,
Put a toy car on a belt sander. The car is the jet, the sander is the conveyor. Holding it in place on the sander is the push of the jet engine. When a real jet takes off do the wheels turn? So are the wheels on the car. If you push the car forward on the belt the the engine would be not at the same speed as the conveyor. Therefore the jet is not making any forward progress, so lift isn't being made around the wings for it to take off.
Well that settles this one, next question please

hoyt_hunter007 · 12-22-2006, 07:01 PM

Quote:

Originally Posted by olman

Invision this,
Put a toy car on a belt sander. The car is the jet, the sander is the conveyor. Holding it in place on the sander is the push of the jet engine. When a real jet takes off do the wheels turn? So are the wheels on the car. If you push the car forward on the belt the the engine would be not at the same speed as the conveyor. Therefore the jet is not making any forward progress, so lift isn't being made around the wings for it to take off.
Well that settles this one, next question please

Thats exactly what i was trying to say, but you made it make more sense...thanks man

Chris · 12-22-2006, 08:37 PM

Boy did I open a can of worms or what!

olman · 12-23-2006, 09:31 AM

What do you do Chris sit back & boggle your mind with questions like this one? Heres something a little more simple & fun. Tie your shoe. Now tie it again, only make your right hand do what your left hand just did & left hand do what your right hand did. Basicly switch roles of your hands. See you've been tying your shoes the same way for years know you don't think about it you could even tie them in the dark if you had to but now you have to think about it, it's kind of like learning all over again. Most people I've tryed this on can do it but it takes time tying is all.
Merry Christmas everyone

12-23-2006, 10:58 AM

Quote:

Originally Posted by olman

Invision this,
Put a toy car on a belt sander. The car is the jet, the sander is the conveyor. Holding it in place on the sander is the push of the jet engine. When a real jet takes off do the wheels turn? So are the wheels on the car. If you push the car forward on the belt the the engine would be not at the same speed as the conveyor. Therefore the jet is not making any forward progress, so lift isn't being made around the wings for it to take off.
Well that settles this one, next question please

Invision this,
Put a toy car on a belt sander. The car is the jet, the sander is the
converyor. Holding it in place on the sander is the push of the engine.
When a real jet takes off do the wheels turn? So do the wheels on the car.

But if you push the car foward once you have set it on the belt the car continues on and that is even with the belt moving faster then the speed of the car, why you ask? Because your hand is like the engines on the plane, both car and jet are being put in motion by a force that is not transmited to the tires which are setting on the belt.

There fore the jet will continue with its foward motion even with the belt spinning at the same or faster rate then the jet is moving.

Get your belt sander out and try it, place your kids car on it and see if you can roll it on it. You will be able to roll you car against the rotation of the belt with out have into push it any faster then if sander was turned off. The only thing that would be different with the sander off or on is the speed at which the tires turn.

Like you said, "Well that settles this one, next question please".

Dredly · 12-24-2006, 07:36 AM

Quote:

Originally Posted by dodgensince74

Invision this,
Put a toy car on a belt sander. The car is the jet, the sander is the
converyor. Holding it in place on the sander is the push of the engine.
When a real jet takes off do the wheels turn? So do the wheels on the car.

But if you push the car foward once you have set it on the belt the car continues on and that is even with the belt moving faster then the speed of the car, why you ask? Because your hand is like the engines on the plane, both car and jet are being put in motion by a force that is not transmited to the tires which are setting on the belt.

There fore the jet will continue with its foward motion even with the belt spinning at the same or faster rate then the jet is moving.

Get your belt sander out and try it, place your kids car on it and see if you can roll it on it. You will be able to roll you car against the rotation of the belt with out have into push it any faster then if sander was turned off. The only thing that would be different with the sander off or on is the speed at which the tires turn.

Like you said, "Well that settles this one, next question please".

Yeah I finally got tired of thinking and looked it up... rack one up for Dodge!

http://www.straightdope.com/columns/060203.html

hoyt_hunter007 · 12-24-2006, 01:36 PM

interesting...i seriously think someone should send this in to mythbusters

justiadak · 02-06-2007, 11:03 PM

Quote:

Originally Posted by Chris

Ok, here's a riddle for you...

You have a 747 sitting on a huge conveyor belt. This conveyor belt is controlled by a computer that precisely matches the speed of the conveyor to the speed of the jet, only going the opposite direction. When they throttle up, will the jet be able to take off?

yes it will take off because it isn't pushing against the force of the conveyor it is pushing against the force of the air.