Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[goblolo]

You XKCD reading bastard goblolo. But who cares, it will be fun.

waht is xkcd?
upd: Lurked a lil, it's comics with inner meanings.

upd2: thx Sheb

[Sheb]

A sciency webcomic.

[goblolo]

I really think this question is super simple if you aren't thinking about it that hard.
Example:

Spoiler: !!SCIENCE!! (click to show/hide)

Simple diagram tells it all.

conveyor doesn't apply force, it applies movement. Which results in friction, not the same as a propelling force.
Guy, you've played hnh! I thought df + hnh pack is for uber tough men!

[goblolo]

"Tent", "Kennel", "House", "Cave".  "Which one is the odd one out?"

I hate questions of this kind! It's stipid! We can say that "Tent" is odd because the word spelling divides plane into 2 pieces (the outer one and a small piece inside 'e' letter). Other words make 3 parts each. "House" is odd because 3rd letter is vowel, other words have consonant one on the 3rd position. "Kennel" is the only word with more than 5 letters, which is definitely odd! Going for "Cave" - let it be the only thing that appears b itself, not being made by humans.

upd: found better solution:
"Tent" is the only word that contains 't'
"Kennel" is the only word that contains 'k'
"House" is the only word that contains 'h'
"Cave" is the only word that contains 'c'
IN YOUR FACE stupid IQ test developer!


The same stupid question is the following: we have numbers 1, 4, 10, 20, 35. What number comes next?
Read the spoilers after thinking about this task a bit.

Spoiler: true answer and the ABSOLUTE TROOO answer inside! (click to show/hide)

Answer: First of all, how did I made this succession? I just took 0. But nobody likes 0, we won't write it. At the first step we add +1 and have 1 now. Write it down. Then add +1 and +2. 1 + 1 + 2 = 4. Write it down. On the third step we'll add +1+2+3: 4 + 1 + 2 + 3 = 10, then 10 + (10) = 20, 20 + (15) = 35. Numbers in brackets are results for 1+2+3+...
Ok, the next number will be 35 + 1 + 2 + 3 + 4 + 5 + 6 = 56.
But wait! We want to say that the number An (on the n'th place) is:
    An = A(n-1) + 1 + 2 + ... + n =
    = A(n-1) + n*(n + 1)/2
So, there is just a formula for the next number.
Ololanswer: Who knows what I am thinking about? Looking at this line 1, 4, 10, 20, 35 the first thought for me (if I didn't created it by myself) will be "Aha! He wrote down stupid polynome F(x) and got F(1) = 1, F(2) = 4, F(3) = 10 ... and want me to calculate F(6)! Ok then!". An I will simply use Lagrange polynomial to write down my own polynom F(x) of 5th degree that results in F(6) = 10. Or F(6) = -27156823169. Ain't it the answer?

[Soadreqm]

1+3=4, 4+6=10, 10+10=20, 20+15=35

So we have the sequence 3, 6, 10, 15

3+3=6, 6+4=10, 10+5=15

So we have the sequence 3, 4, 5; the next one obviously being 6.

15+6=21; 35+21=56.

Seriously, polynomials? These things can sometimes have many different answers, but if the FIRST one you think of is "let's mathematically brute-force this bitch!", you're doing it wrong.

[goblolo]

1+3=4, 4+6=10, 10+10=20, 20+15=35

So we have the sequence 3, 6, 10, 15

3+3=6, 6+4=10, 10+5=15

So we have the sequence 3, 4, 5; the next one obviously being 6.

15+6=21; 35+21=56.

Seriously, polynomials? These things can sometimes have many different answers, but if the FIRST one you think of is "let's mathematically brute-force this bitch!", you're doing it wrong.

But what if I used other methods, like: 8, 28, 77, 176. What's next?

Spoiler (click to show/hide)

1 + 1 = 2, 2 + 2 = 4, 4 + 3 = 7, 7 + 4 = 11, 11 + 5 = 16, 16 + 6 = 22
2 * 4 = 8, 4 * 7 = 28, 7 * 11 = 77, 11 * 16 = 176, 16 * 22 = 352

Using your approach we'll have:
8 + 20 = 28, 28 + 49 = 77, 77 + 99 = 176
20 + 29 = 49, 49 + 50 = 99
29 + 21 = 50
21 ? lolwut! didn't found anything 1-2-3-like! Stoopid task!

I don't speak about using the brute-force method everywhere, I just want to show that some problems may have multiple solutions, more or less obvious ones. And being a mathematician, I don't like it because they are not precise enough. Maybe it is because of knowing more mathematical applications: for someone it is simplier to subtract and divide things while trying to find the succession he is used to (e.g. 1-2-3 or 3-6-9), but for me it is simplier to use a 100% reliable method and don't bother with it anymore.
Talking about this in general, a problem should either have one the superobvious solution (like 1-2-3-?), or the only one. In case of several solutions possible, the problem itself is considered a little stupid. Just a bit.

[Soadreqm]

8, 28, 77, 176. What's next?

Spoiler (click to show/hide)

1 + 1 = 2, 2 + 2 = 4, 4 + 3 = 7, 7 + 4 = 11, 11 + 5 = 16, 16 + 6 = 22
2 * 4 = 8, 4 * 7 = 28, 7 * 11 = 77, 11 * 16 = 176, 16 * 22 = 352

Using your approach we'll have:
8 + 20 = 28, 28 + 49 = 77, 77 + 99 = 176
20 + 29 = 49, 49 + 50 = 99
29 + 21 = 50
21 ? lolwut! didn't found anything 1-2-3-like! Stoopid task!

If every series DID follow the same pattern, these questions would be pretty easy. I thought it might have been
82 87 71 76
giving us a nice, repeating +5,-10,+5,-10... pattern, the numbers being grouped like 1,2,2,3,3,3,4,4,4,4... making the next number
76-10=66, 66+5=71
667
But I figured that was way too complicated to be the right one. :/

I don't speak about using the brute-force method everywhere, I just want to show that some problems may have multiple solutions, more or less obvious ones. And being a mathematician, I don't like it because they are not precise enough. Maybe it is because of knowing more mathematical applications: for someone it is simplier to subtract and divide things while trying to find the succession he is used to (e.g. 1-2-3 or 3-6-9), but for me it is simplier to use a 100% reliable method and don't bother with it anymore.
Talking about this in general, a problem should either have one the superobvious solution (like 1-2-3-?), or the only one. In case of several solutions possible, the problem itself is considered a little stupid. Just a bit.

1-2-3-5! It's the Fibonacci sequence!
I think you're kind of missing the point of IQ tests like these. It's about finding patterns, not doing calculations. Brute-forcing the numbers with a Lagrange polynomial gives you one plausible pattern. Another one for all examples so far is x_n<x_n+1. Neither of those is usually the "correct" one, for obvious reasons.

[foil]

It wont take off unless air is moving over the wings, which wont happen if its sitting still with the wheels spinning on a conveyor belt.

What happens if it did lift off the conveyor?  Just magically float above the ground @ 0 mph and slowly build up speed without just dropping out the sky?

Kinda how i doubt a car on a dyno will build up downforce.

[Soadreqm]

It wont take off unless air is moving over the wings, which wont happen if its sitting still with the wheels spinning on a conveyor belt.

What happens if it did lift off the conveyor?  Just magically float above the ground @ 0 mph and slowly build up speed without just dropping out the sky?

If the plane is sitting still, what is making the wheels spin? >:]

[foil]

It wont take off unless air is moving over the wings, which wont happen if its sitting still with the wheels spinning on a conveyor belt.

What happens if it did lift off the conveyor?  Just magically float above the ground @ 0 mph and slowly build up speed without just dropping out the sky?

If the plane is sitting still, what is making the wheels spin? >:]

The treadmill/conveyor belt lol.

[Soadreqm]

foil:

A plane is standing on a 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 the opposite direction). Can the plane take off?

The conveyor belt moves at the same speed the plane does, to the opposite direction. If the plane is sitting still, so is the belt.

[Phmcw]

This is a trick question : you'll imagine the plane stationary, because you're used to walking or to drive, two situation where the trust is gained by pusing the ground (thus the conveyor make you stationarry). The plane use it's motor to push the air (basically) to go forward, thus the conveyor will do nothing, exept make the wheels roll faster. It would be a very expensive way to make taking off a bit harder (due to incrased friction and general "I'm trying to take of with a plane on a gigant conveyor belt shenanigans).

[DJ]

The wheels won't spin if the plane isn't moving forward, because the wheel are in fact unpowered.

[Soadreqm]

Hang on, because you're pushing against the air, the automated treadmill that tracks and matches the speed of the plane won't work?

Bluh!?

Surely because the plane is going forward, the treadmill will match that to cancel it, meaning that despite it pushing against the air, it won't go forward?

Matching the speed of the airplane does not cancel it. The rolling friction of the wheels is fairly low. If the plane is moving forward at 300 km/h, the treadmill is rolling backward at 300 km/h, and the wheels are spinning with the tangential velocity of 600 km/h.

[foil]

I think what the question was aiming for is, if the plane is sitting still but the runway is moving like a conveyer belt would it generate lift?

It either a trick question about the unpowered wheels rotation speed not making difference to flight, or if a plane sitting on a treadmill thats doing 200mph would it generate lift from wings while the plane isnt moving at all?