riddle

True and good job :D

Hmm... One off the top of my head.


If I'm L today, what will I be when I'm M?

Either your the alphabet, 18 or a detective on the hunt for Kira (Death Note).

Mello

Haw haw, a good guess, there IS a clue there. But close! (Both of you) XD

what... 9th from A? Or maybe 4th from M?

I'd like to write one of my all-time favourite riddles down. Behold: the conveyor belt riddle. (Answer googling forbidden.)

It's kind of old (So is the egg and chicken one, so what?) and it doesn't seem to be anywhere on the forums yet.

I have yet to meet a person who could give me the correct answer to this one. (Well, I googled it really hard, and encountered several solutions which both approved and disapproved my personal solution on this matter.) I'd like to hear my fellow fakkers ideas.

I have seen fifty page discussion topics on this matter (Which didn't even come to an conclusion at the end.), I have seen even physics professors fail it, it's that sneaky.

Our object of interest: an airplane. A normal propeller turbine engine powered one which requires lift from the wings to take off.

Our culprit: an infinite long conveyor belt instead of a runway, which features the ability to move into the opposite direction with the exact same velocity of the airplane's wheels.

No particular weather effects, materials, or anything like that involved.

I hope this prevents some confused questions on the riddle itself, now on to my question: Will the airplane be able to take off?

The subconscious post - count addict in me says "+1" maybe?
Otherwise... LM is a sailboat type so maybe your a sailboat? Or it is Landmine? *ponders and whistles*

yes they did this on mythbusters and it worked

Okay just to make sure I understood it correctly :)
The conveyor increases the speed in relation to the plane's increase in speed as the plane doesn't have the ability to start at full speed right away.

Now incase it is that, it should be possible, as the airstream is at the same velocity that is needed for takeoff. In the end it is not the "speed" of the airplane that makes it lift off, but speed of the airstream at the wings of the airplane that allows the takeoff. Thus incase you have the conveyor belt switched on, the airplane would have to counter it's speed, thus increasing the speed of the airstream, while standing still. So basicly once the needed airstream speed in knots is reached, the airplane will basicly "shoot forward" lifting off at the normal minimum speed needed to get up into the air.
At least that is my theory.

once again its been done heres vid

He wanted the theory with an explanation i guess. I couldn't care less for the video. If you don't understand the theory behind it, but just say "it works", you didn't solve it :)

Sorry for being a bit harsh there, but no need to spoil the fun :)

some people might like vid sense it does literally show it working and no offense taken

You just refer to a solution which is not even your own, without any explanation or anything which would require you to give it even a little bit of thought, what's the point of that other than completely ruining it for others?

Was my theory right by the way? I took what I knew from sailing / sail plane flying, physics and (as ridiculous as it may sound) from the fitness studio (those running bands, dunno their name).

Give me some time there - I still have a hard time on such matters in english.

I haven't watched that Mythbuster solution, I didn't even know they took their time for this one - but I'm not really surprised.



That is correct. Both the conveyor belt and the airplane are at the same speed all the time. If the airplane is standing still, so is it's 'runway'.



I'm not telling you yet, keep on puzzling.

But imagine your scenario from a third point of view, which would make the plane look literally frozen in place.

Now logical, no movement done equals to no airstream pressing against the wings, which would make no takeoff possible.

Well, the plane is moving forward, it is just holding a relative position on the band. I know it sounds like a contradiction, but still when your on a running band, you also feel the air of moving forwards, it is just that the band serves as a purpose to keep you in one relative position.
It is the same with the airplane, thus an airflow is created above and below the wings and the plane will be able to lift off.

I never got to use a treadmill before, but I think that airstream you feel has a different reasoning behind it.

The human way of running isn't a 'consistent motion'*, on stated treadmill it consists of getting pushed back and 'jumping' forward again, thus the airstream.

But your theory states that the airplane isn't even able to move an inch due to it's wheels which are on permanent contact with the conveyor belt, and even if the plane would be able to 'jump' for a little headwind, it would not be enough for a takeoff.

*[size=7]I, once again, made this term up with my own translation from german. No warranty there, but you should get the draft.[/h]

*get's another thought* Wait a sec... wheels /slaps himself. Of course that is the solution. As it is wheels that are NOT connected to the engine (means basicly that they are free running except if you are pulling a break) you just need to use a certain counterforce to get your own wheels into movement. Once they have begun movement and you increase the throttle on the airplane, the airplane will be able to move forward. It is all within the energy conservation law, as long as you will be able to use a bit more throttle to negate the energy loss through heat / contact. That way even if the conveyor belt builds up the same speed as the aircraft, the aircraft having a non direct force conversion (i.e. from the engine to the propeller instead of the wheels), will be able to lift off.

Movement is not the issue here, it's not like the conveyor belt would prevent the wheels from moving.



You are basically trying to say that the airplane is in advantage over the conveyor belt due to the fact that it isn't directly motorized?

If we follow that path and make it a race of engines both sides would probably speed up to an infinite amount until one side perishes under the extreme friction, but this is not an option, since this is a riddle about the laws of physics and not about various materials and their flaws. Let's get away from that theory.

By the way, I just watched that Mythbuster video, and I'm a little disappointed. It doesn't seem to be a very accurate measurement of speeds, the airplane used is a lightweight and they didn't get that much into detail when explaining it.