Small questions and answers-thread

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Ricky
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Re: Small questions and answers-thread

Postby Ricky » Tue Sep 08, 2009 9:27 am

An interesting question...

Hold you hand a few inches from your mouth.
If you breath gently on your hand, it feels warm.
If you blow n your hand, it feels cold.

Why the difference?
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Hubsu
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Re: Small questions and answers-thread

Postby Hubsu » Tue Sep 08, 2009 1:08 pm

Your hand feels warm on the exhale because water wapour condensing in your hand releases energy. During inhale, the opposite effect is true, but in a slightly smaller degree because of the moist difference between your hand and the ambient air is smaller than between your hand and your exhaled air.

Edit: Ooopsies, I misread your question in the first place! I feel a warming effect in both cases :P

It might feel slightly colder in the "blow as hard as you can"-scenario because the air rushing through evaporates the just condensed water again thus the net warming effect is smaller in the blowing scenario than in the "gently breeze" scenario.
Last edited by Hubsu on Tue Sep 08, 2009 1:13 pm, edited 1 time in total.

Ricky
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Re: Small questions and answers-thread

Postby Ricky » Tue Sep 08, 2009 1:13 pm

I don't think you have understood me...

The faster you exhale, the colder it feels on your hand.
"Study the past, if you would divine the future"
-Confucius

"I am pedantic, I'm just being overshadowed by Ricky so it isn't as noticable as it would else have been"
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Re: Small questions and answers-thread

Postby Hubsu » Tue Sep 08, 2009 1:14 pm

Ricky wrote:I don't think you have understood me...


Aye, I did. Read the edit :P

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Re: Small questions and answers-thread

Postby 2nd.Dragoon » Tue Sep 08, 2009 1:15 pm

Richard it's evident that you have too much time on your hands!
When are you back at work? :?

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Re: Small questions and answers-thread

Postby Ricky » Tue Sep 08, 2009 1:18 pm

2nd.Dragoon wrote:Richard it's evident that you have too much time on your hands!
When are you back at work? :?


:D

I'm at work now - but I think up these questions on my own time ;) Did you see i posted your picture?
"Study the past, if you would divine the future"
-Confucius

"I am pedantic, I'm just being overshadowed by Ricky so it isn't as noticable as it would else have been"
-Skua

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Re: Small questions and answers-thread

Postby 2nd.Dragoon » Tue Sep 08, 2009 1:24 pm

Yes, the Mae West Water Front at Benghazi, you can see more of these on my facebook page.
(Along with Ram, Dave the Sniper and others)

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ram
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Re: Small questions and answers-thread

Postby ram » Wed Sep 09, 2009 12:21 am

2nd.Dragoon wrote:Yes, the Mae West Water Front at Benghazi, you can see more of these on my facebook page.
(Along with Ram, Dave the Sniper and others)


The classic pictures are awesome :)
Colors are beautiful and deceiving.

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Re: Small questions and answers-thread

Postby Stix » Sun Sep 20, 2009 5:55 pm

Ricky wrote:An interesting question...

Hold you hand a few inches from your mouth.
If you breath gently on your hand, it feels warm.
If you blow n your hand, it feels cold.

Why the difference?

Physics and biology, my turf again :P
First of all, let's make it clear that the difference lays mostly in perception, regardless of the speed, the temperature of the air you exhale differs little.
When you breathe gently, it feels warm because the air coming out of your body has taken on the temperature of your body which is usually warmer then the air around you.
When blowing strongly however, the air rushes by your hand and carries away what little heat is in the outer layer of your skin. If your skin is moist from i.e. sweat, this effect increases as it also helps in evaporating the moisture which naturally causes a cool sensation.
It's quite similar to a windy day or windstill, while in reality the temperature is the same, the windy day feels colder.
Or most clearly yet, consider a fan. A regular household fan does not cool the air, it merely increases it's speed which causes a cooler sensation.

Next question please? I'm starting to like this thread!
Because common sense, isn't all that common.

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Re: Small questions and answers-thread

Postby LionSE1 » Fri Sep 25, 2009 1:14 pm

Question for you all!

If the earth is in the middle of the sun and the moon how does this happen:

I was talking to an Australian friend the other day at 7am who said it was night and he could see the moon, I advised him I could also see the moon, and also the sun!

So how come I can see the Moon, and he can aswell, but only I can see the sun?

:?

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Re: Small questions and answers-thread

Postby Oli » Sat Sep 26, 2009 4:53 am

LionSE1 wrote:Question for you all!
If the earth is in the middle of the sun and the moon how does this happen:
I was talking to an Australian friend the other day at 7am who said it was night and he could see the moon, I advised him I could also see the moon, and also the sun!
So how come I can see the Moon, and he can aswell, but only I can see the sun?
:?

Cos the moon is off to one "side".
Think of it as a "L" shape, Sun at the top of the L, Moon at the far right tip and Earth at the bottom corner.
From the corner someone can see the top and the right hand tip, but someone on the "bottom" of the corner can't see the top because they've got the bulk of Earth in the way of the view.

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Re: Small questions and answers-thread

Postby Pika » Mon Jun 14, 2010 7:52 pm

Anyone is buying the 2012 end of the world because I think everyone is gonna be allright and is something like 1000 A.D when everyone freaked out or something like 2000 :-?
All right, they're on our left, they're on our right, they're in front of us, they're behind us... they can't get away this time. Lieutenant General Lewis B."Chesty" Puller

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Re: Small questions and answers-thread

Postby LionSE1 » Thu Oct 28, 2010 1:34 pm

What way would chairs be designed if our legs bent the same way as an Ostrictches?

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Re: Small questions and answers-thread

Postby Pika » Sat Nov 06, 2010 2:27 pm

Same way only we would be using stool instead of normal chairs :D



Cheers !
All right, they're on our left, they're on our right, they're in front of us, they're behind us... they can't get away this time. Lieutenant General Lewis B."Chesty" Puller

Ricky
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Re: Small questions and answers-thread

Postby Ricky » Sat Nov 06, 2010 3:57 pm

Probably something like these ergonomic chairs...

Image
"Study the past, if you would divine the future"
-Confucius

"I am pedantic, I'm just being overshadowed by Ricky so it isn't as noticable as it would else have been"
-Skua


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