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What Are the Most Counter-intuitive Facts? Options
Epiphileon
Posted: Tuesday, July 3, 2018 3:50:15 AM

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Aphelion is coming at 67,000mph and will be here Friday July 6, @ 12:46 pm!

When I posted this today on my Facebook page, I commented afterwards, "Still ranks in my top 5 counter-intuitive facts of all time.
Which is a guess as I don't know what the other 4 are offhand."

We are in the middle of a heatwave, 5-7 days of temperatures above 90 degrees, but on Friday the Earth will be at the furthest away from the sun it gets in its orbit. Of course this is only counter-intuitive for the folks in the Northern Hemisphere.

What are the most counter-intuitive things you know?

Question authority. How do you know, that you know, what you know?
BobShilling
Posted: Tuesday, July 3, 2018 6:27:46 AM
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Clouds are very heavy. Even a small cumulus cloud can weigh as much as two elephants and scientists estimate that an average-sized cumulus cloud could contain as much as 200 tonnes of water.

Cumulonimbus clouds, which are up to 10 times denser and 1,000 times larger than cumulus clouds, could weigh as much as one million tonnes.


http://www.bbc.co.uk/guides/zsbwjxs#zyggr82
Epiphileon
Posted: Tuesday, July 3, 2018 7:17:40 AM

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Thanks Bob I didn't know that. It made me think, obviously something that weighed that much could not possibly float in the atmosphere. I came to the conclusion that there is no such thing as a cloud, in the same way there is no such thing as a forest. A cloud is an enormous number of water molecules in very close proximity, as a forest is just a great many trees in close proximity.

M'lady is not looking at me like I'm from outer-space!

Question authority. How do you know, that you know, what you know?
Lotje1000
Posted: Tuesday, July 3, 2018 8:27:05 AM

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If you are in orbit around the planet and you want to catch up with something else that is in orbit around the same planet, your best bet is to slow down. (Similarly, if you want the other object to catch up to you, your best bet is to speed up.) That is because if you slow down, you go to a lower orbit that is smaller/shorter than the one the object is on.

Courtesy for this one is the Kerbal Space Program game and this Quora question.
progpen
Posted: Tuesday, July 3, 2018 8:28:42 AM

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That sunlight exerts physical pressure. The solar wind pushes against the Earth's magnetosphere (auroras are the result). There has also been experimentation showing that solar sails can propel a space craft.

Nolite te bastardes carborundorum
Oscar D. Grouch
Posted: Wednesday, July 4, 2018 5:28:48 AM

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BobShilling wrote:
Clouds are very heavy. Even a small cumulus cloud can weigh as much as two elephants and scientists estimate that an average-sized cumulus cloud could contain as much as 200 tonnes of water.

Cumulonimbus clouds, which are up to 10 times denser and 1,000 times larger than cumulus clouds, could weigh as much as one million tonnes.


http://www.bbc.co.uk/guides/zsbwjxs#zyggr82


Heavy rain.

An inch of rain falls on an acre of land and weighs 113.3 tons.

Or...

A centimeter of rain falls on an hectare of land and weighs 100 metric tons.
Drag0nspeaker
Posted: Thursday, July 5, 2018 9:13:50 AM

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Only 18% of the world's population live in the western hemisphere. 82% live in the east.
Only 10% of the world's population live in the south.

Europe is in the near East (with the exception of Brittany, Spain and Portugal).
Most of Britain is in the West - but not Essex, East Sussex, Kent, Suffolk and Norfolk. (No wonder they're a bit 'odd' over there!).

Of all the people who have ever reached 65 years of age in the history of the human race, half of them are still alive.



Wyrd bið ful aræd - bull!
Hope123
Posted: Thursday, July 5, 2018 1:17:18 PM

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Which ball falls fastest, a basketball, or tennis ball? i.e. a heavy ball vs. a lighter ball. Intuition says the heavier ball.

But the force of gravity tries to make everything accelerate downward at EXACTLY the same rate, no matter how light or heavy it is. This means that if you dropped a basketball and a tennis ball at the same time (from the same height) they will hit the ground at the same time (try it!).

So why if you drop a feather and a rock at the same time, do you know that the rock will hit the ground first and the feather will fall much more slowly? This time intuition works.

The problem with dropping stuff near the surface of the earth is that gravity is not the only force acting - there is also air resistance. Air tends to make stuff fall more slowly, especially light objects, which is why the feather hits the ground last. Since tennis balls and basketballs are quite heavy, at least compared to feathers, we don't easily notice the effect of air resistance on these (although it's still there).

If there were no air, all objects would fall at exactly the same rate. In other words, if you went to the moon (where there is no atmosphere) and dropped a feather, a rock, a tennis ball and a basketball, they would all hit the ground at the same time.

The past is to be respected/acknowledged, not worshipped. It is in our future we will find our greatness. Pierre Trudeau
Sarrriesfan
Posted: Thursday, July 5, 2018 3:41:02 PM

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Hope123 wrote:
Which ball falls fastest, a basketball, or tennis ball? i.e. a heavy ball vs. a lighter ball. Intuition says the heavier ball.

But the force of gravity tries to make everything accelerate downward at EXACTLY the same rate, no matter how light or heavy it is. This means that if you dropped a basketball and a tennis ball at the same time (from the same height) they will hit the ground at the same time (try it!).

So why if you drop a feather and a rock at the same time, do you know that the rock will hit the ground first and the feather will fall much more slowly? This time intuition works.

The problem with dropping stuff near the surface of the earth is that gravity is not the only force acting - there is also air resistance. Air tends to make stuff fall more slowly, especially light objects, which is why the feather hits the ground last. Since tennis balls and basketballs are quite heavy, at least compared to feathers, we don't easily notice the effect of air resistance on these (although it's still there).

If there were no air, all objects would fall at exactly the same rate. In other words, if you went to the moon (where there is no atmosphere) and dropped a feather, a rock, a tennis ball and a basketball, they would all hit the ground at the same time.


Commander David Scott of the Apollo 15 mission did the experiment within a hammer and a feather, but the same principle applies.

https://m.youtube.com/watch?v=4mTsrRZEMwA

My counterintuitive fact, few people are killed by lava when a volcano erupts, it does generally flow fast like a river as is often shown in Hollywood movies, it's dense and viscous and moves so slowly most people can walk away from it.

What kills more people are ash falls, lahars and pycroclastic flows (although I still prefer the term Nuee Ardente glowing cloud).

I lack the imagination for a witty signature.
rmberwin
Posted: Thursday, July 12, 2018 6:11:21 PM

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A peach is just a fuzzy nectarine.

"Great art should never be mushed up!!"
Absinthius
Posted: Friday, July 13, 2018 4:24:40 AM

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rmberwin wrote:
A peach is just a fuzzy nectarine.


Absolutely not! A nectarine is just a bald peach.

Look, how about this? Let's pretend we've had the row and I've won. See? It saves a lot of effort.
Jyrkkä Jätkä
Posted: Friday, July 13, 2018 7:56:38 AM

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A peach is just a hairy apple ;-)


In the beginning there was nothing, which exploded.
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