Will it take off?

[2Fbodcru]

I thought about it a little more, and I am now pretty sure that you guys are right - the plane would probably take off

[Christopherrr]

okay, I think I'm starting to see how it could fly...

physorg.com

[Jeff_in_Atl]

Ya'll are going to hate me for this but if you put a car on the tread mill under the same conditions the car would move forward, Here is why. The question says the car moves in one direction while the ground moves in the other direction. The point is the you have to base the movement from a fixed object. You can not base the car movement to the moving ground and the moving ground to a non moving ground. You have to base both from the same point or you won't ever start motion. So the car start to accelerate, remember the car has to move to a fixed object before the ground will move in the opposite direction, when the car is moving at 1 mph based on the ground speed the ground is moving the opposite direction at 1 mph but the car speedometer is reading 2 mph. The car has to go 1 mph to keep up with the ground plus 1 mph to achieve to forward movement to make the ground move 1 mph in the other direction.

[Jeff_in_Atl]

You can't use that analogy. The car's wheels are driven. An airplane freewheels like in neutral.

Are you talking to me?

[Jay 02 TA ws6]

Ya'll are going to hate me for this but if you put a car on the tread mill under the same conditions the car would move forward, Here is why. The question says the car moves in one direction while the ground moves in the other direction. The point is the you have to base the movement from a fixed object. You can not base the car movement to the moving ground and the moving ground to a non moving ground. You have to base both from the same point or you won't ever start motion. So the car start to accelerate, remember the car has to move to a fixed object before the ground will move in the opposite direction, when the car is moving at 1 mph based on the ground speed the ground is moving the opposite direction at 1 mph but the car speedometer is reading 2 mph. The car has to go 1 mph to keep up with the ground plus 1 mph to achieve to forward movement to make the ground move 1 mph in the other direction.

This is where my first post of relative motion comes in to play. From the control tower, the car could move 1 mph forward and the the treadmill move 1 mph backwards... that would mean the wheels are turning at 2 mph.

Or... as observed from the control tower, the car could be stationary if the wheel's velocity exactly matched the treadmill's.

[Jay 02 TA ws6]

okay, I think I'm starting to see how it could fly...

physorg.com

Your freebody diagram is in error because there is no rearward acceleratory force acting on the plane. The rearward force of acceleration acts upon the wheels only - and because the wheels spin freely, they exert no force on the plane. Therefore, the only acceleratory force on the plane is forward (actually, its rearward, thus moving the plane forward - but you get the idea), and the plane moves and will take off.

You are stuck picturing the same thing I was - a stationary plane to an observer in the control tower - yet in reality, that's a physical impossibility.

[Jeff_in_Atl]

This is where my first post of relative motion comes in to play. From the control tower, the car could move 1 mph forward and the the treadmill move 1 mph backwards... that would mean the wheels are turning at 2 mph.

Or... as observed from the control tower, the car could be stationary if the wheel's velocity exactly matched the treadmill's.

That's correct. The similarity of the car to the plane is that the speed is measured to a non moving point not to the speed of the treadmill or the speed indicator in the car or airplane.

[Joe 1320]

Your freebody diagram is in error because there is no rearward acceleratory force acting on the plane. The rearward force of acceleration acts upon the wheels only - and because the wheels spin freely, they exert no force on the plane. Therefore, the only acceleratory force on the plane is forward (actually, its rearward, thus moving the plane forward - but you get the idea), and the plane moves and will take off.

You are stuck picturing the same thing I was - a stationary plane to an observer in the control tower - yet in reality, that's a physical impossibility.

Bingo. Jay is seeing things clearly.

[TraceZ]

Bingo. Jay is seeing things clearly.

Yet technically there is a drag force acting on the airplane in the opposite direction as the thrust force.

[Jay 02 TA ws6]

Yet technically there is a drag force acting on the airplane in the opposite direction as the thrust force.

OK, OK... but if you want to get that technical, then you have to take in to account the friction of the bearings and that the wheels actually do exert a miniscule amount of force on the plane in a rearward direction... we have to ignore the small things like that, because the thrust force that moves the plane forward is much, much greater.

[Joe 1320]

The point is that the force of the engine is being exerted on the air, not the treadmill. The wheels are freewheeling and only used in this application to support weight.

[Jeff_in_Atl]

I'd say we have beat this horse to death. 117 beatings so far.

[TODD 2000 V6 CAMARO]

That's it...dangit! I'm calling MythBusters! I'm sure if anyone can come up with a real-world test for this, then they can. Let's all find a way to submit ideas to the show and get those suckers to settle this once and for all! LOL I'm serious. Stop laughing.

By the way...it will fly.

[Jeff_in_Atl]

That's it...dangit! I'm calling MythBusters! I'm sure if anyone can come up with a real-world test for this, then they can. Let's all find a way to submit ideas to the show and get those suckers to settle this once and for all! LOL I'm serious. Stop laughing.

By the way...it will fly.

Here's the link to mythbuster's submissions page. I have not read to see if this one is there or not.
http://community.discovery.com/1/Ope...4&f=9701967776

[Red20170]

I'd say we have beat this horse to death. 117 beatings so far.

No fights either....