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Okay, What The Hell...


Krisboats

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it may be worth recalling that in maths, our teacher made us do similar tricks, and it went like:

choose a number, n

add 2, n+2

multiply it by 2, 2n+4

take away 4, 2n

and divide by your original number, 2

it would always give the answer of two

i think this uses a similar trick

:)

FINALLY! GCSE MATHS WAS ACTUALLY USEFUL

(psych)

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This has been posted two or three times before - I'm surprised you haven't seen it before. It's pretty simple really:

If I said pick any 2 digit number. Take the second digit and subtract that from the original. In this example obviously every answer you get is a multiple of 10, so I could have a board where 10,20,30,40 etc had the same symbol. That would be too obvious though.

They tell you to add the digits together, then subtract them from the total. They *could* have said subtract second digit (as above) THEN subtract the second - which would give the same answer. So you have the multiple of 10 as before (n times 10), minus 'n'. So the only possible answers are 9, 18, 27, 36 etc (multiples of 9). If you look, all the multiples of 9 are the same symbol, the rest are irrelevant.

It's just pretty simple maths, but with a bit of extra crap to confuse you.

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I hate it when people change their names i have no idea who people are anymore.

The wording of the question says that the tredmill matches the speed of the plane.

So when the plane trys to move forward, it does. But the tredmill speeds up and up to impossibly high speeds. The friction in the bearings of the wheels adventually starts pulling the plane backwards, keeping it stationalry.

Edited by JT!
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A plane only needs to be doing 150-200mph (depending on type) to take off. That means that at the very most, the wheels would be spinning backwards at 400mph, but even past the 125mph (plane speed) or 250mph (wheel speed) mark, the plane could still maintain the lift with one wheel blowing out or something similar.

So either way, you're shit out of luck.

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plus doesn't the plane need low pressure to go under the wing and high pressure to go over it? or whichever round it is to get the aerofoil thing to become effective? if its not travelling anywhere then the air particles aren't going to go under + over the wing....

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The plane is not driven by the wheels.

Stand on a skateboard on a treadmill with a large fan on your back and you're going to go forwards whatever speed the treadmill is going.

It will take off.

He's right, sorry jt but like you i was adamant the thing wouldn't take off last time we had this discussion. I've long since seen that it will in fact take off. The above example is as good as you can get. Basically as the wheels are just spinning on axles they can go as fast as they like, so long as the plane has air being pushed it can take off. The wheel speed and the floor travelling backwards is irrelevant.

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The wheel speed and the floor travelling backwards is irrelevant.

Not entirely. As this is entirely ficticious and there aren't set values there are certain possibilities which would mean it can't take off. The main one im thinking of is to do with the tyres. These may well be designed for certain speeds, by doubling the speed at which the tyres will have to provide support for the entire plane its majorly increasing the chance of failure. If the tyres fail you might not be able to take off as there will be increased friction etc etc. Crap like that really, although this is being rather pedantic.

As a generalisation it will take off, otherwise it'd be like saying planes can't fly just because there is a slim possibility that they would fail in mid air.

Edited by ZeroMatt
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A plane only needs to be doing 150-200mph (depending on type) to take off. That means that at the very most, the wheels would be spinning backwards at 400mph, but even past the 125mph (plane speed) or 250mph (wheel speed) mark, the plane could still maintain the lift with one wheel blowing out or something similar.

So either way, you're shit out of luck.

...So the aerodynamics of the plane have nothing to do with it then ?

Jarrod

Edit....Haha I bet I look like a right cnut now don't i ?

Edited by Pashley26
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...So the aerodynamics of the plane have nothing to do with it then ?

Jarrod

no the aerodynamics of the plane have everything to do with it, mark is saying the wheels of the plane have nothing to do with it, and he is right. (other than the tiny amount of friction caused on the treadmill. )

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the plane doesn't take off because as it is propelled, the treadmill compensates, meaning the plane essentially goes nowhere.

but the clever bit is, it's nothing to do with that. WINGS need air moving under them to create lift, thus the plane can push as hard as it likes with its jets, if it is not physically moving into the air (e.g if it was on a treadmill) then there will be no lift, and believe it or not, that means no take off

:)

unless its a harrier or another VTOL, in which case, the force goes down, the treadmill doesn't move in that direction and it will fly ;)

however, if there was a PHAT fan blowing at the plane at the same time, maybe it would take off

hmm

i have a better answer anyway

and perhaps i speak for most of the forum AND INFACT the entire internet when i say...

f**k OFF WITH THE PLANE AND THE TREADMILL!!

=]

Edited by Disasterboy
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