Odd Ball Interview Questions

I know the answer to the plane question already, I remember the fun and frolics that ensued from the big thread about it a while back.

So have we decided whether elephants float or not?
 
The plane has wheels which will rotate as fast as is necessary to counter the speed of the treadmill and allow the plane to move forward.

Unless you assume that the treadmill can reach an infinite speed in one direction, in which case I'll just assume that the plane's axles are frictionless and the wheels can reach an infinite speed in the other direction. Failing that, we'll just have to agree that the axles will melt and the plane will shoot off the back of the treadmill at near infinite speed and completely write off the air traffic control tower.
 
Ceryndrion said:
8 pennies, split into two piles of 4, keep the four that weigh least... step 1
take the four, split into two piles of 2, keep the two that weight least.. step 2
take the last two, split and weigh.. the result is obvious.. step 3

This is actually quite a simple logic question..
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Wrong. The questions was 'in less that three steps'.

The correct answer is:

Take six of the eight coins and put three on either side of the scales. If they balance then the lighter coin is in the two remaining. Take those two and place onse one either side of the scales to find the lightest.

If the three-on-three didn't balance then take the three from the lighest side, put one coin on each side and put the third coin to one side. If the scales balance then the coin you put to the side is the lightest, if the scales don't balance then you still know which is the lightest.
​

Answer in 'less than 3'. Logical, not simple!
 
Humpty said:
Wrong. The questions was 'in less that three steps'.

The correct answer is:

Take six of the eight coins and put three on either side of the scales. If they balance then the lighter coin is in the two remaining. Take those two and place onse one either side of the scales to find the lightest.

If the three-on-three didn't balance then take the three from the lighest side, put one coin on each side and put the third coin to one side. If the scales balance then the coin you put to the side is the lightest, if the scales don't balance then you still know which is the lightest.
​

Answer in 'less than 3'. Logical, not simple!
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Very clever! :cool:
 
Kingy said:
But the engines generate power resulting in speed, not lift?

It feels like thrust ought to have something to do with this?
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Thrust creates the forward motion, which in turn rotates the wheels, if the conveyor is moving at the same speed as the plane is moving forward, then the plane goes nowhere and does not create any lift.

That's my understanding of it.
 
Not a logic question as such, but I once got asked to decide what flavour ice-cream various Windows Operating systems would be and give reasons for my answer (I think it was 2000, XP and Vista at the time)

That really was the weirdest interview question I've ever been asked!
 
Sp00n said:
Thrust creates the forward motion, which in turn rotates the wheels, if the conveyor is moving at the same speed as the plane is moving forward, then the plane goes nowhere and does not create any lift.

That's my understanding of it.
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It doesn't matter, as the wheels will rotate to counter the hindrance of the treadmill.

If a plane is moving forwards at 10mph on stationary ground, the wheels are moving forwards at 10mph.
If a plane is held stationary, somehow, but the ground (treadmill) is moving backwards at 10mph, the wheels are moving forwards at 10mph.
If a plane is moving forwards at 10mph on ground (treadmill) that is moving backwards at 10mph, the wheels are moving forwards at 20mph.

So the plane will take off, simply because it can't be held still so long as the wheels can move.
 
Sp00n said:
Thrust creates the forward motion, which in turn rotates the wheels, if the conveyor is moving at the same speed as the plane is moving forward, then the plane goes nowhere and does not create any lift.

That's my understanding of it.
Click to expand...

I'm not sure if it's the way it's written, or simply the way I'm reading it, but he does only say that the treadmill matches the planes speed, not that the plane achieves a take off speed while on the treadmill, or is that what you were saying?

Ie, the engines have started up, but are just idling?
 
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