hmmm.... physics question for you guys....

[zeegler]

Re: hmmm.... physics question for you guys....

You're not thinking. The Thrust of the plane does not cause it to take off. The thrust of the engines cause the plane to accelerate in relation to the air around it regardless of the speed of the conveyor belt. Imagine you are on a conveyor belt wearing roller skates, and you are holding on to a rope that is attached to the far end of the room. Your arms are the "engines" that provide thrust. The rope is the medium that the thrust is acting against. Now, when you pull that rope towards you, you are going to move towards the other end of the room, regardless of whether the belt is going 1mph or 50mph.

So back to the plane. Thrust does not cause the plane to lift off. Thrust causes the plane to accelerate (not in relation to the ground, but in relation to the air). The plane WILL accelerate, and as it accelerates, the wings WILL create lift, and the plane WILL take off.

[zeegler]

Re: hmmm.... physics question for you guys....

VitaminG and Rob are the only ones who get it. The rest of you need to take some physics lessons, or get some common sense.

[Number Of The Priest]

Re: hmmm.... physics question for you guys....

I say we strap some rollerskates and a jetpack on Gary and try this. [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img]

Zeegs, you're saying that the thrust is causing the plane to accelerate relative to the air. Why is the air suddenly moving? Because of thrust? That makes no sense. [img]/images/graemlins/crazy.gif[/img]

[VitaminG]

Re: hmmm.... physics question for you guys....

[ QUOTE ]
and I stood on the same treadmill (now set to 200mph) on roller skates

[/ QUOTE ]
see, now I'm thinking you're ignoring parts of my argument to strengthen your own [img]/images/graemlins/smile.gif[/img]

[Number Of The Priest]

Re: hmmm.... physics question for you guys....

[img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img]

Guys, it's all about frames of reference! Do the supermarket checkout counter thing! It's the closest thing to this experiment without strapping on jetpacks and rollerskates. [img]/images/graemlins/laugh.gif[/img]

[VitaminG]

Re: hmmm.... physics question for you guys....

[ QUOTE ]
I say we strap some rollerskates and a jetpack on Gary and try this. [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img]

[/ QUOTE ]You would! [img]/images/graemlins/laugh.gif[/img]

[ QUOTE ]
Zeegs, you're saying that the thrust is causing the plane to accelerate relative to the air. Why is the air suddenly moving? Because of thrust? That makes no sense. [img]/images/graemlins/crazy.gif[/img]

[/ QUOTE ]
The air isn't suddenly moving. The air is still (relatively). The engine moves the plane by thrusting against the still air. It would be like you standing with your back to a wall and pushing back with your arms - it makes you move forward.

[zeegler]

Re: hmmm.... physics question for you guys....

[ QUOTE ]
I say we strap some rollerskates and a jetpack on Gary and try this. [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img]

Zeegs, you're saying that the thrust is causing the plane to accelerate relative to the air. Why is the air suddenly moving? Because of thrust? That makes no sense. [img]/images/graemlins/crazy.gif[/img]

[/ QUOTE ]

Holy shit! Is there a smiley that is pulling his hair out?

The air is not moving. I never said it was. That's the point. Read my example with the rope. The rope represents the air. It is not moving. The propulsion unit (arms) pushes/pulls the air (rope) causing acceleration.

[zeegler]

Re: hmmm.... physics question for you guys....

[ QUOTE ]
[img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img]

Guys, it's all about frames of reference! Do the supermarket checkout counter thing! It's the closest thing to this experiment without strapping on jetpacks and rollerskates. [img]/images/graemlins/laugh.gif[/img]

[/ QUOTE ]

No, it's not even close. There is nothing tethering the plane in a stationary position, which is exactly what you are doing with your hand.

[zeegler]

Re: hmmm.... physics question for you guys....

See, this is why I could never be a teacher. I would end up smacking the kids and telling them "that's just the way it is, accept it, or be stupid" [img]/images/graemlins/laugh.gif[/img]

[Number Of The Priest]

Re: hmmm.... physics question for you guys....

Here's the scenario from the start.

1.) Put the plane on the conveyor belt.

2.) Start up the conveyor belt, and watch the plane move backwards. Note the plane is still off, and its wheels are not moving.

3.) The pilot turns the plane on to counter its backward movement, to the point where it's matching the speed of the conveyor belt. The wheels are spinning at THAT speed, not double.

4.) By this time, the belt hits 300mph. The pilot matches this speed and the plane is going 300mph. The wheels are ALSO going 300mph. The pilot looks out the window and sees that he's not moving relative to the air or the ground. He can wave to his wife standing there who is simultaneously getting her children to point fingers and laugh at VitG, RobRR, and Zeegs. Just kidding guys. [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/wink.gif[/img] [img]/images/graemlins/wink.gif[/img] [img]/images/graemlins/wink.gif[/img]

5.) At this point, the pilot can be a total moron and pull up on the flight controls. If it's a fighter jet with a thrust-to-weight-ratio greater than 1, he MIGHT be able to take off like a freakin' space shuttle. Anything else, the plane will go forward a little bit and smash into the ground. [img]/images/graemlins/laugh.gif[/img]

6.) The wife and kids mourn the loss of the pilot. [img]/images/graemlins/laugh.gif[/img]

[Number Of The Priest]

Re: hmmm.... physics question for you guys....

[ QUOTE ]
See, this is why I could never be a teacher. I would end up smacking the kids and telling them "that's just the way it is, accept it, or be stupid" [img]/images/graemlins/laugh.gif[/img]

[/ QUOTE ]

We used to have relativity arguments in high school physics class exactly like this one. There'd always be one smartass student (usually me [img]/images/graemlins/laugh.gif[/img] ) trying to refute everything the teacher is saying. [img]/images/graemlins/laugh.gif[/img]

[LouSiffer]

Re: hmmm.... physics question for you guys....

Yup, Zeegs is right. After fixxing another drink, I just realized something.... the plane will gain forward momentum. It is pushing off the air which does not move with the conveyor. The wheels would then turn at 200MPH assuming thrust was 100 MPH forward and the conveyor in moving 100 MPH in the opposite direction.

I was wrong, but, Zeegs comment about everyone needing "common sense" was kind of uncalled for.Lou

[Number Of The Priest]

Re: hmmm.... physics question for you guys....

Actually, I made a blunder with step 5. There's no air passing over the wings, since the plane is still sitting there at full throttle, hence the elevators on the wings will do nothing. The plane will remain on the conveyor belt, and our pilot lives to see his family, and join them in laughing at the aforementioned parties. Just kidding again. [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/wink.gif[/img]

[Number Of The Priest]

Re: hmmm.... physics question for you guys....

WTF mate, this is starting to hurt my head. I have homework to do. And no, it's not physics. I'm glad I was done with that in my freshman year. [img]/images/graemlins/laugh.gif[/img]

[VitaminG]

Re: hmmm.... physics question for you guys....

[ QUOTE ]
Here's the scenario from the start.

1.) Put the plane on the conveyor belt.

[/ QUOTE ]ok, so far so good.

[ QUOTE ]
2.) Start up the conveyor belt, and watch the plane move backwards. Note the plane is still off, and its wheels are not moving.

[/ QUOTE ]I'm with you so far....

[ QUOTE ]
3.) The pilot turns the plane on to counter its backward movement, to the point where it's matching the speed of the conveyor belt. The wheels are spinning at THAT speed, not double.

[/ QUOTE ] and THERE...is the fatal flaw in your argument. This would work if the plane was wheel-driven. The wheels would be accelerated until they matched the speed of the belt moving under them. You're ignoring how a jet engine or propeller actually generates forward movement.

[ QUOTE ]
4.) By this time, the belt hits 300mph. The pilot matches this speed and the plane is going 300mph. The wheels are ALSO going 300mph. The pilot looks out the window and sees that he's not moving relative to the air or the ground. He can wave to his wife standing there who is simultaneously getting her children to point fingers and laugh at VitG, RobRR, and Zeegs. Just kidding guys. [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/laugh.gif[/img] [img]/images/graemlins/wink.gif[/img] [img]/images/graemlins/wink.gif[/img] [img]/images/graemlins/wink.gif[/img]

[/ QUOTE ] see point 3 [img]/images/graemlins/laugh.gif[/img]

[ QUOTE ]
5.) At this point, the pilot can be a total moron and pull up on the flight controls. If it's a fighter jet with a thrust-to-weight-ratio greater than 1, he MIGHT be able to take off like a freakin' space shuttle. Anything else, the plane will go forward a little bit and smash into the ground. [img]/images/graemlins/laugh.gif[/img]

[/ QUOTE ] I thought you said that if the belt was to match the speed of the plane, it couldn't move forward? Even a little bit? [img]/images/graemlins/laugh.gif[/img]

[ QUOTE ]
6.) The wife and kids mourn the loss of the pilot. [img]/images/graemlins/laugh.gif[/img]

[/ QUOTE ]The wife and kids mourn the loss of zeegler's sanity. [img]/images/graemlins/smile.gif[/img]