Can A Fly Stop A Train?! (more Technical)

[manuel]

Depends how long the half life of the parent atom of the radioactive substance is?

Or do i have the wrong end of the stick...

ok yes i should have made that clear ... it is equally likely that an atom decays as doesnt...

[munkee]

Yeah, i knew someone would bring that up, but my points till valid.

This is a good one. You have greater chance of winning the car if you change your mind, and go with the other door. It seems like you still have a 50/50 chance. But if you stick with the same door, you still have a 2/3 chance that you have a goat.

Why should you change door? you could have been right the first time. Its 50/50 so theres no point in changing. Sticking with the same door doesnt mean you have 2/3 chance at all.. it still means you have 50/50

[JT!]

Why should you change door? you could have been right the first time. Its 50/50 so theres no point in changing. Sticking with the same door doesnt mean you have 2/3 chance at all.. it still means you have 50/50

Hehe, it's hard to get your heard round. If the chances arn't 50/50. If it were, it wouldn't be such a well know riddle.

The chances of picking a goat at the start are 2/3. When the presenter reveals a goat, and you have 2 doors left, the chances are 2/3 that you still have the goat.

If you had to choose between the 2 doors from the start, it would be 50/50. But becuase you've had to choose from 3 to start with, it alters your chances from 50/50.

You have more chances of winning the car if you switch.

[Davetrials]

oh my god, what the dammed hell is going on... i dont want to read this post again for fear of mental breakdown.

[spangler]

There is a video to prove the plane takes off.

Someone must know where it is. I saw it on offtopic ages ago.

Here is a silly vid.

oh and

The monty hall solution

Edited November 20, 2006 by spangler

[Dan6061]

Here is a silly vid.

I was thinking of it a different way..

So the plane faces the same was as the conveyor is moving, and isn't turned on..

It wont take off if it was the like the way in the video.

[Gavyn.]

for the plane one

if i understood it right

the plane is sitting on a prefectly level freely rolling tread mill, the planes wheels are freely moving aswell it's engines are on and it's weight is keeping it in one position as the engines add thrust the plane applies a force behind it in order to move forward but the tread mill applies an equal force forwards so the wheels begin to spin at the same speed as the tread mill so the plane stays in a fixed position.

in order for a plane to take off air must pass over and under the wings at great speed and providing down force

but because the plane is in a fixed position there is no air resistance (much like running on a tread mill indoors compared with running out doors where air resistance is a problem) no air resistance means no air is passing over and under the wings of the plane so the plane can not take off no matter how much pasty it gives.

as for the monty one

you've got a 2/3 chance of it being in the second one than it being in the original one you chose.

EDIT:i was pretty close with how the conveyer belt worked here's the original question

A plane is standing on runway that can move (some sort of band conveyer). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in opposite direction).

Edited November 20, 2006 by Gavyn L

[Extreme_biker0]

for the plane one

if i understood it right

the plane is sitting on a prefectly level freely rolling tread mill, the planes wheels are freely moving aswell it's engines are on and it's weight is keeping it in one position as the engines add thrust the plane applies a force behind it in order to move forward but the tread mill applies an equal force forwards so the wheels begin to spin at the same speed as the tread mill so the plane stays in a fixed position.

in order for a plane to take off air must pass over and under the wings at great speed and providing down force

but because the plane is in a fixed position there is no air resistance (much like running on a tread mill indoors compared with running out doors where air resistance is a problem) no air resistance means no air is passing over and under the wings of the plane so the plane can not take off no matter how much pasty it gives.

as for the monty one

you've got a 2/3 chance of it being in the second one than it being in the original one you chose.

EDIT:i was pretty close with how the conveyer belt worked here's the original question

You're so right. Noaoaot!

[JT!]

But here's the thing. I've the belt tracks the speed of the plane. It will never move. Because the planes speed will always be 0.

However if we're talking about the wheels, it's a different matter. Like i said before, the only reason the question is comlicated is because the question is so vague.

[Extreme_biker0]

But here's the thing. I've the belt tracks the speed of the plane. It will never move. Because the planes speed will always be 0.

However if we're talking about the wheels, it's a different matter. Like i said before, the only reason the question is comlicated is because the question is so vague.

Someone quoted the actual riddle above. The conveyor matches the speed of the plane in the oposite direction. So, if the plane travels at 20mph along the conveyor, the conveyor will go 20mph inthe opposite direction. Relative speed between conveyor and plane: 40mph. Result: planes wheels spin a bit quicker, but it still takes off.

It must be in your genes weather you can get it or not.

[endofreak]

But here's the thing. I've the belt tracks the speed of the plane. It will never move. Because the planes speed will always be 0.

However if we're talking about the wheels, it's a different matter. Like i said before, the only reason the question is comlicated is because the question is so vague.

I think it's purposely vague. It tricks you into thinking that the conveyor can hold the plane still when in reality a conveyor could never hold a plane still no matter how fast it was going because a plane does not transfer it's energy through the ground in the same way that a car does.

[Tomm]

It's a completely theoretical question though. Obviously there isn't a conveyor belt big enough for a plane, and powerful enough to rotate a few hundred yards of tarmac. It's just a bit of fun.

Someone quoted the actual riddle above. The conveyor matches the speed of the plane in the oposite direction. So, if the plane travels at 20mph along the conveyor, the conveyor will go 20mph inthe opposite direction. Relative speed between conveyor and plane: 40mph. Result: planes wheels spin a bit quicker, but it still takes off.

It must be in your genes weather you can get it or not.

I understand all of the issues involved, but it completely depends on how you interpret the wording. It basically depends on whether the treadmill is matching the speed of the plane or the wheels. So to say people are wrong when we don't even know what we're talking about is a bit stupid really.

[Extreme_biker0]

It's a completely theoretical question though. Obviously there isn't a conveyor belt big enough for a plane, and powerful enough to rotate a few hundred yards of tarmac. It's just a bit of fun.

I understand all of the issues involved, but it completely depends on how you interpret the wording. It basically depends on whether the treadmill is matching the speed of the plane or the wheels. So to say people are wrong when we don't even know what we're talking about is a bit stupid really.

Hm.. excuses

If you *were* to imagine it as matching the *wheels* instead of the plane, you would end up with a positive feedback loop in the direction the plane initally travelled, which, in seconds would overcome the bearings in the wheels and completely destroy the plane.

For example, planes wheels go 2mph, conveyor matches, this makes wheels go 4mph, conveyor matches, 8mph, matches, 16, 32, 64 etc etc...

Nobody has thus far mentioned this possibility therefore we can just assume that everyone who did not conclude that the plane took off plain *got it wrong*

Edited November 21, 2006 by Extreme_biker0

[Tomm]

1. The conveyor belt matches the wheels, it doesn't lag behind otherwise that just completely ruins the hypothetical scenario.

2. It's completely hypothetical so the resistance in the bearings in not relevant, we're talking ideal perfect situations here. If you're not then I'm sure there are a million things much more important to think about (E.g. where to get a mile-long treadmill from)

[Extreme_biker0]

1. The conveyor belt matches the wheels, it doesn't lag behind otherwise that just completely ruins the hypothetical scenario.

2. It's completely hypothetical so the resistance in the bearings in not relevant, we're talking ideal perfect situations here. If you're not then I'm sure there are a million things much more important to think about (E.g. where to get a mile-long treadmill from)

ZOMG u r33tard!!

The conveyor matches the speed of the plane! Not the wheels! Else the positive feedback loop described above is the result! Since nobody has mentioned this they're assuming the speed of the plane!

THEREFORE!!>>>>!!!!>>> if it's the speed of the plane.... because the wheels are FREEMOvInG iT MeAnS they just spin at twice the speed!!!!!

Takeoff speed @ 120 knots, they are easily capable of 240 KnOtS!!!!

ZOMG

kthx

Edited November 21, 2006 by Extreme_biker0

[JT!]

Belt matches the speed of the plane, there for the speed of the plane though the air is always 0.

It will not take off.

[mat hudson]

but it wont be, jt, because the drive isnt delivered through the wheels. the engines push the air and the air is not effected by the treadmill.

[adamtrials]

Belt matches the speed of the plane, there for the speed of the plane though the air is always 0.

It will not take off.

Groundspeed or airspeed?

It doesnt matter if the conveyer is going at a million knots in any direction, the plane will still take off.

(Assuming no friction in wheels)

[mat hudson]

[Has anyone seen my shoe?]

[JT!]

Mat, my love for you has just doubled becuase of that pic.

Anyway, i still don't get it. And i've read the whole thred.

[Brian Bleech]

Rightio random paint explanation ….

- Imagine your on a bike with stabilisers and only the stabilers are on converter belts.

- The conveyor belt matches how fast you go on the bike.

- You will still go forward because the bike isn’t on the conveyer belt.

- the stabiliser wheels however will spin twice as fast, but have no effect on your speed because they are not attached to your drivetrain.

It’s the same principle for the plane, it took me a while to get it last time!

[attachmentid=8303]

[Has anyone seen my shoe?]

I get it now.

[JT!]

Yeah, but the belt matches the speed of the plane.

Why's everyone so concerned about what the wheels are doing when it's the plane we're talking about.

[mat hudson]

jt, imagine you are standing on the side of a treadmill with a pram. you push the pram along the tredmill from the side. if the treadmill stopped would speed up? no! you wouldnt! the thrust for the pram isnt coming from the wheels so it just isnt effected. same with the plane.

Edited November 22, 2006 by mat hudson