Australian Politics Forum - How human intuition can be wrong:

Bobby. Gold Member Offline Australian Politics Posts: 105031 Melbourne Gender:	How human intuition can be wrong: Dec 1^st, 2023 at 9:33pm Answer the question before watching the video. It seems easy. This video explains it.
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Dnarever Gold Member Offline Australian Politics Posts: 58584 Here Gender:	Re: How human intuition can be wrong: Reply #1 - Dec 1^st, 2023 at 10:10pm Bobby. wrote on Dec 1^st, 2023 at 9:33pm: Answer the question before watching the video. It seems easy. This video explains it. I didn't believe the answer was 3 - Thought that was obvious. The answer is 4. that isn't obvious.
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Bobby.

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Re: How human intuition can be wrong:
Reply #2 - Dec 1^st, 2023 at 10:16pm

Dnarever wrote on Dec 1^st, 2023 at 10:10pm:

Bobby. wrote on Dec 1^st, 2023 at 9:33pm:

Answer the question before watching the video.

It seems easy.

This video explains it.

I didn't believe the answer was 3 - Thought that was obvious.

The answer is 4. that isn't obvious.

But it's 3 if you roll the circle along a straight line

but not around a circle!

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Dnarever

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Re: How human intuition can be wrong:
Reply #3 - Dec 1^st, 2023 at 10:50pm

Bobby. wrote on Dec 1^st, 2023 at 10:16pm:

Dnarever wrote on Dec 1^st, 2023 at 10:10pm:

Bobby. wrote on Dec 1^st, 2023 at 9:33pm:

Answer the question before watching the video.

It seems easy.

This video explains it.

I didn't believe the answer was 3 - Thought that was obvious.

The answer is 4. that isn't obvious.

But it's 3 if you roll the circle along a straight line

but not around a circle!

If you work out the circumference of both circles you get 3. This is because the error is that the effective radius of the outer circle is radius 1 plus radius 2. i.e if the small circle radius is 2 then the second is 6. these numbers give the result of 3.

The distance between the centre point and the centre of the outer circle is 8. R1 + R2

Formula 2 X R X Pi

It seems crazy.

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Dnarever

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Re: How human intuition can be wrong:
Reply #4 - Dec 1^st, 2023 at 10:52pm

Bobby. wrote on Dec 1^st, 2023 at 10:16pm:

Dnarever wrote on Dec 1^st, 2023 at 10:10pm:

Bobby. wrote on Dec 1^st, 2023 at 9:33pm:

Answer the question before watching the video.

It seems easy.

This video explains it.

I didn't believe the answer was 3 - Thought that was obvious.

The answer is 4. that isn't obvious.

But it's 3 if you roll the circle along a straight line

but not around a circle!

If you make the 2 circles it rotates 4 times. once per quarter.

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Bobby. Gold Member Offline Australian Politics Posts: 105031 Melbourne Gender:	Re: How human intuition can be wrong: Reply #5 - Dec 1^st, 2023 at 10:57pm DNA, Quote: It seems crazy. Our intuition was wrong. That is why all engineering designs have to be tested as they are based on assumptions that sound perfect but could be wrong.
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AusGeoff Gold Member Offline Sage of Gippsland Posts: 5999 Victoria Gender:	Re: How human intuition can be wrong: Reply #6 - Dec 1^st, 2023 at 11:16pm Intriguing, but beyond my pay grade. Thanks for the link.
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Sprintcyclist Gold Member Offline OzPolitic Posts: 40751 Gender:	Re: How human intuition can be wrong: Reply #7 - Dec 2^nd, 2023 at 1:56am that is a mathematical question, not much to do with intuition
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Bobby.

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Re: How human intuition can be wrong:
Reply #8 - Dec 2^nd, 2023 at 5:49am

AusGeoff wrote on Dec 1^st, 2023 at 11:16pm:

Intriguing, but beyond my pay grade. Grin

Thanks for the link.

But it's well explained in the video -
you always have to add 1 to the result because the circle causes an extra rotation.
That accounts for sidereal time on Earth being one extra day per year i.e
not 365.25 days but 366.25 days per year. (approx)

https://www.realclearscience.com/blog/2022/09/08/how_many_times_does_the_earth_r...

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Bobby. Gold Member Offline Australian Politics Posts: 105031 Melbourne Gender:	Re: How human intuition can be wrong: Reply #9 - Dec 2^nd, 2023 at 5:54am Sprintcyclist wrote on Dec 2^nd, 2023 at 1:56am: that is a mathematical question, not much to do with intuition But even those who wrote the exam got it wrong. Almost everyone gets it wrong.
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Bias_2012

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Re: How human intuition can be wrong:
Reply #10 - Dec 2^nd, 2023 at 9:06am

Bobby. wrote on Dec 2^nd, 2023 at 5:54am:

Sprintcyclist wrote on Dec 2^nd, 2023 at 1:56am:

that is a mathematical question, not much to do with intuition

But even those who wrote the exam got it wrong.
Almost everyone gets it wrong.

The examiners got it wrong probably because they are not mechanical engineers. If they are, I wouldn't trust anything they'd design or make

My intuition told me straight away that radii shouldn't be taken into consideration, that only the curved surfaces should be considered to solve the question

However, I would have used those radii while quickly tearing out two paper circles to run the small one around the large one, to get the answer that way

The reason why the straight ribbon didn't work, is because it wasn't curved, obviously. The small circle travels a greater distance on a curved line than on a straight line

That's why the rack & pinion steering in a car is higher geared than two circular gears that have the same number of teeth, something I wish Kia had thought about when they designed the steering in my Cerato, it's way too high geared, it needs a smaller pinion

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Bobby.

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Re: How human intuition can be wrong:
Reply #11 - Dec 2^nd, 2023 at 10:32am

Bias_2012 wrote on Dec 2^nd, 2023 at 9:06am:

Bobby. wrote on Dec 2^nd, 2023 at 5:54am:

Sprintcyclist wrote on Dec 2^nd, 2023 at 1:56am:

that is a mathematical question, not much to do with intuition

But even those who wrote the exam got it wrong.
Almost everyone gets it wrong.

The examiners got it wrong probably because they are not mechanical engineers. If they are, I wouldn't trust anything they'd design or make

My intuition told me straight away that radii shouldn't be taken into consideration, that only the curved surfaces should be considered to solve the question

However, I would have used those radii while quickly tearing out two paper circles to run the small one around the large one, to get the answer that way

The reason why the straight ribbon didn't work, is because it wasn't curved, obviously. The small circle travels a greater distance on a curved line than on a straight line

That's why the rack & pinion steering in a car is higher geared than two circular gears that have the same number of teeth, something I wish Kia had thought about when they designed the steering in my Cerato, it's way too high geared, it needs a smaller pinion

It shows are bad human thinking can be and
why everything needs to be checked.
Even teams of university professors can make appalling errors.

The answer is 3 if you roll the circle along a straight line -
but not around a circle! - then it's 4.

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Bias_2012

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Re: How human intuition can be wrong:
Reply #12 - Dec 2^nd, 2023 at 11:11am

Bobby. wrote on Dec 2^nd, 2023 at 10:32am:

The answer is 3 if you roll the circle along a straight line -
but not around a circle! - then it's 4.

That's correct

When you are driving your car and cut a corner, you will get around that corner quicker than the car behind that didn't cut the corner but is traveling at the same speed

Do you get it now?

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Bobby.

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Re: How human intuition can be wrong:
Reply #13 - Dec 2^nd, 2023 at 11:21am

Bias_2012 wrote on Dec 2^nd, 2023 at 11:11am:

Bobby. wrote on Dec 2^nd, 2023 at 10:32am:

The answer is 3 if you roll the circle along a straight line -
but not around a circle! - then it's 4.

That's correct

When you are driving your car and cut a corner, you will get around that corner quicker than the car behind that didn't cut the corner but is traveling at the same speed

Do you get it now?

I understand it now.
The fact that you are rotating around a circle causes the extra 1 to be added to the answer.
You can see it with 2 identical coins as shown in the video.

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Laugh till you cry

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Re: How human intuition can be wrong:
Reply #14 - Dec 2^nd, 2023 at 11:29am

Bias_2012 wrote on Dec 2^nd, 2023 at 11:11am:

Bobby. wrote on Dec 2^nd, 2023 at 10:32am:

The answer is 3 if you roll the circle along a straight line -
but not around a circle! - then it's 4.

That's correct

When you are driving your car and cut a corner, you will get around that corner quicker than the car behind that didn't cut the corner but is traveling at the same speed

Do you get it now?

BuyArse2012 is a genius.

Report to Chez Gordon immediately to receive a professorship in WTF Knowledge.

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Please don't thank me. Effusive fawning and obeisance of disciples, mendicants, and foot-kissers embarrass me.

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