Airplane / Treadmill Voting Booth

**Art Shirk** · 02-20-2007, 03:06 PM

Originally Posted by focus

I stayed at a Holiday Inn Express last night.

So far, my vote is with you...but DJSapp has the whole dentistry thing. I just need to pick a side here without using my own brain. Funny thing is, I wouldn't spend a minute trying to figure out if the plane will take off, but I would spend hours wondering whether the plane actually exists.

**DJSapp** · 02-20-2007, 03:07 PM

Originally Posted by commonlaw

So far, my vote is with you...but DJSapp has the whole dentistry thing. I just need to pick a side here without using my own brain. Funny thing is, I wouldn't spend a minute trying to figure out if the plane will take off, but I would spend hours wondering whether the plane actually exists.

I knew I should have taken my commitment to internet dentisty more seriously

**Brock Landers** · 02-20-2007, 03:10 PM

Originally Posted by commonlaw

but I would spend hours wondering whether the plane actually exists.

Were you a philosophy minor?

edit- I majored and got a degree in physics, but I hated mechanics

**dbp** · 02-20-2007, 03:19 PM

How about a slight rewording of the problem to hopefully sidestep the difference between the two take-off camps' interpretations...

- Plane is on huge treadmill
- Plane starts accelerating forward while treadmill stays stationary
- When the plane reaches 10 mph, the treadmill starts moving in the opposite direction at 750 mph

I would contend that the plane will continue to accelerate and take off. In fact, the treadmill will still have almost no affect in this scenario.

**The AD** · 02-20-2007, 03:21 PM

B.S. with high honors in mechanical engineering from Michigan State
M.S. in mech. eng. (thesis dealt with fluid mechanics)
10 years experience in aero engineering

...and obviously none of these things helped me one iota in figuring out whether the airplane would fly or not.

**DJSapp** · 02-20-2007, 03:26 PM

Originally Posted by dbp

How about a slight rewording of the problem to hopefully sidestep the difference between the two take-off camps' interpretations...

- Plane is on huge treadmill
- Plane starts accelerating forward while treadmill stays stationary
- When the plane reaches 10 mph, the treadmill starts moving in the opposite direction at 750 mph

I would contend that the plane will continue to accelerate and take off. In fact, the treadmill will still have almost no affect in this scenario.

O RLY?
...............................

**Art Shirk** · 02-20-2007, 03:45 PM

Originally Posted by Brock Landers

Were you a philosophy minor?

edit- I majored and got a degree in physics, but I hated mechanics

It was one of my majors. I had one major that I assumed would help me get a job and one that allowed for copious bong rips.

Looks like The AD has some street cred too.

note Sartre in the avatar. I like to think that that picture was taken as he was contemplating the many ways to tell the Pulitzer Prize people to eat a bag of dicks.

**Brock Landers** · 02-20-2007, 03:46 PM

Originally Posted by commonlaw

It was one of my majors. I had one major that I assumed would help me get a job and one that allowed for copious bong rips.

Looks like The AD has some street cred too.

Philosophy majors = nerds or potheads

**BurnHard** · 02-20-2007, 03:47 PM

Credentials: I'm an Aerospace Engineer AND Mathematician.

Solution: The airplane WILL take off.

Explanation: Thrust is provided by the jet engines. Thrust is needed to overcome Drag. Drag is made up of aerodynamic drag, and friction drag on the wheels. The friction drag on the wheels/bearings will be *marginally* higher on the spinning treadmill, but will continuously diminish as the airplane gains speed and the lift increases, thus reduction wheel friction.

Source of confusion: The problem statement is slightly confusing because it says something about the treadmill spinning at the same speed of the aircraft. This could induce some people to believe that the two velocities cancel each other out, whereas the truth is that the wheels will simply spin twice as fast (remember, the wheels of the aircraft are free spinning).

- B

**Cirquerider** · 02-20-2007, 03:54 PM

Originally Posted by Viva

But in a fruity world there wouldn't be any fruit resistance and that just messes all the equations up.

Good God, the earth is spinning at over 1000 MPH. We are all going to be flung off into space

BTW, the plane takes off...unless the tires blow up from excessive speed before lift is achieved.

**Art Shirk** · 02-20-2007, 03:56 PM

Originally Posted by Brock Landers

Philosophy majors = nerds or potheads

Otherwise signified as:

If Ph ) N V Po
~N
.
. . Po

and very true.

**Tippster** · 02-20-2007, 04:22 PM

Originally Posted by commonlaw

Otherwise signified as:

If Ph ) N V Po
~N
.
. . Po

and very true.

You forgot =\Doritos\= in that equation somewhere...

**smitchell333** · 02-20-2007, 04:32 PM

So if the plane does take off :

- does it need to travel the same distance down the runway it normally would?

**Franz Klammer** · 02-20-2007, 04:43 PM

Originally Posted by smitchell333

So if the plane does take off :

- does it need to travel the same distance down the runway it normally would?

Yes, except for a small adjustment for the friction which slows its acceleration.

**Franz Klammer** · 02-20-2007, 04:49 PM

I just planted the problem in the office - it's mayhem ...

**f2f** · 02-20-2007, 04:54 PM

i just planted the problem at the physics division of a national lab. it's not mayhem.

**Franz Klammer** · 02-20-2007, 05:03 PM

Originally Posted by f2f

i just planted the problem at the physics division of a national lab. it's not mayhem.

Mayhem has ended with everyone agreeing that the plane will take off (without my influence). On the other hand, the blue-eyed problem was a non-starter. Everyone (all Econ PhDs) knew how to solve it or knew the answer.

**f2f** · 02-20-2007, 06:17 PM

Originally Posted by Franz Klammer

Everyone (all Econ PhDs) knew how to solve it or knew the answer.

i realized that after reading the comments there. oh well, i have no degree in economics

**huck4bucks** · 02-20-2007, 06:30 PM

After giving it more thought. I kinda think the plane will take off now--in theory. Can I switch my vote?

For all you non-taker-offers, think about this: the wheels are free rolling, meaning that the net effect of the treadmill is 0. Sure, the wheels will be spinning at 800mph and the treadmill will be whirling at 400mph, but the plane will still move forward enough to create airflow over the wings.

Hmmm.... I'm not 100% yet, but I see where the flyers are coming from now.

**Telenater** · 02-20-2007, 06:41 PM

You guys are funny......

Villagers: (enter yelling) A witch! A witch! We've found a witch! Burn her! Burn her!

(After Sir Bedimere gets the crowd to admit that they dressed her up as a witch, their only basis for accusing her is that one of them claims that she turned him into a newt. But because he "got better", they need some way of determining her guilt).

Bedimere: there are ways of telling if she's a witch. What do you do with witches?

Villagers: Burn them!

Bedimere: And what do you burn, apart from witches?

Villagers: Wood?

Bedimere: Right! So why do witches burn?

Villagers: Because they're made of wood?

Bedimere: Right! . Now, what else do you do with wood?

Villagers: Build bridges with it!

Bedimere: But do we not also build bridges from stone; does wood float in water?

Villagers: Yes.

Bedimere: And what else floats in water?

King Arthur: (after more confused suggestions from the villagers) A duck!

Bedimere: Right! So, if she weighs the same as a duck, she'd float in water, and she must be made of wood, so.

Villagers: A witch! Burn her!

(They weigh the woman on a large scale with a duck in the other balancing basket, but inexplicably the scales do not tilt one way or the other. As the villagers drag the woman away, the witch looks at the camera and says with resignation "it was a fair court".)

Bedimere: (to King Arthur) Who are you who are so wise in the ways of science?

**f2f** · 02-20-2007, 06:44 PM

telenater gets -10 points for failing to use recently-made-available-technology

**ill-advised strategy** · 02-20-2007, 06:48 PM

I guess I should preface by saying I'm not really that surprised....but this thread is proof that 37% of us are retarded.

I'm sorry so many of your moms dropped you on your heads when they were getting out of their monster trucks.

that is all.

**huck4bucks** · 02-20-2007, 07:05 PM

Nope...sticking with No. The treadmill will always be at the same speed as the wheels, which means, there's no way the plane will ever move anywhere. If you think about it, the question isn't whether the plane will take off or not, it's will the plane move. If the plane can move, eventually it will take off. If the plane doesn't move it will never take off (we've already gone over lift dynamics).

So if the question is will the plane ever move relative to the ground (not the treadmill), I say the answer is no. The treadmill will always counteract the forward motion of the plane with an equal and opposite backwards motion. The plane will remain motionless relative to an on-looker. The plane will not take off. I'm sticking with my original vote.

**f2f** · 02-20-2007, 07:16 PM

huck4bucks, if you're running on a threadmill and i push you in the back would you move forward? even if the threadmill suddenly switched to double the speed?

**P_McPoser** · 02-20-2007, 08:22 PM

LOL summit. I love this answer.

Originally Posted by Summit

For those morons who think that thhe treadmill accellerates infinitely and holds the plane motionless relative to the ground while its wheels spin (which it does not, the question precludes this), as the treadmill reaches a high enough speed, air resistance will cause the treadmill to generate a wind which will eventually approach a speed which will eventually allow takeoff even in your fruity world.

(yes it will be flying with an indicated airspeed of 150 knots, an indicated groundspeed of... well thats impossible to calculate in this insane twisted version of reality... a true groundspeed of zero (up until the point of takeoff then the plane accelerates)

in this twisted world the plane may stall if it doesn't accelerate suficiently before leaving the generated wind effect zone of the treadmill... but it will take off