says dave in new york city: “i love that this note contains a fairly detailed explanation of lord kelvin’s formulation of the second law of thermodynamics. and a helpful diagram!”
related: when you get down to it
when ph.d.s get frustrated
June 3rd, 2007 · 91 comments
FILED UNDER: "helpful" advice · temperature · university · visual aids
91 responses so far ↓
#1
Rigby
That’s truely the best. I love the diagram.
Jun 3, 2007 at 5:34 pm rating: +4
#2
TTFK
So he’s a PhD, and he makes a drawing of hot air FALLING?
Jun 3, 2007 at 6:06 pm rating: +22
#3
Catsoup
Pfft. I’d be more impressed if he’d used blue ink to indicate the cold air.
Jun 3, 2007 at 6:51 pm rating: +28
#4
Artorios
Hahaha
Jun 3, 2007 at 7:26 pm rating: 0
#5
Anhoni
All he had to say was “Don’t run the A/C with the window open, it wastes electricity.”
Jun 3, 2007 at 8:02 pm rating: +1
#6
Mark Davis
this note isn’t passive aggressive. it has a specific request and logical rational reasons.
Jun 3, 2007 at 8:47 pm rating: +13
#7
Suzi
Okay, I’ve been reading this web site obsessively since I stumbled upon it a week or so ago, and this is my favorite one so far. Brilliant.
Jun 3, 2007 at 9:26 pm rating: +1
#8
Jordan
Mark Davis is right, in the end.
Jun 3, 2007 at 10:16 pm rating: 0
#9
andyfox1979
truly a scientist.
Jun 3, 2007 at 10:31 pm rating: 0
#10
Adam
Absolutely the best PA note thus far. Let’s start a ‘note of the week’ or something here
Jun 4, 2007 at 12:14 am rating: +1
#11
babychaos
I reckon Mark Davis wrote the note.
Cheers
BC
Jun 4, 2007 at 11:52 am rating: 0
#12
Michael
The room won’t necessarily get hotter. If the cold air blown into the room minus the hot air generated by inefficiencies in the unit is greater than zero then you have a net decline in heat. It doesn’t matter that the A/C blows hot air outside because that shouldn’t effect the temperature inside. It could make a difference if there’s a constant draft going into the room that draws all the heat from the unit in with it but that probably doesn’t happen too often. It still wastes a lot of electricity though. Blowing a fan over a bucket of cold tap water would be a lot more efficient.
Jun 4, 2007 at 12:03 pm rating: 0
#13
phampants
i’m glad ph.d. students have so much time
Jun 4, 2007 at 12:48 pm rating: +1
#14
Veritas
Am I mistaken or did he spell it vary instead of very?
Jun 4, 2007 at 12:52 pm rating: 0
#15
jane
Best one so far….
Jun 4, 2007 at 6:21 pm rating: 0
#16
OPTIMUSCRIME.COM » Living With Engineers
[...] Today, via the Globe and Mail, we found PassiveAggressiveNotes, a blog dedicated to the snarky notes left by roommates. Our favourite is a rejoinder to keep the window closed near the air conditioner: [...]
Jun 4, 2007 at 6:27 pm rating: 0
#17
V
hmmm…hard to determine whether this is P-A or just plain TMI. Sometimes, it’s best to just say what needs sayin’ (like Anhoni stated), without the lesson.
Jun 4, 2007 at 6:58 pm rating: 0
#18
Top Posts « WordPress.com
[...] when ph.d.s get frustrated says dave in new york city: “i love that this note contains a fairly detailed explanation of lord kelvin’s […] [...]
Jun 4, 2007 at 6:59 pm rating: 0
#19
Hooray for nerdy notes! « nudnik.
[...] passive-aggressive notes from roommates, neighbors, coworkers and strangers [...]
Jun 4, 2007 at 8:38 pm rating: 0
#20
kat
i love this one. the best so far!
Jun 5, 2007 at 2:33 am rating: 0
#21
CoFactors » Blog Archive » A Blog of Notes
[...] particularly this one, which provides a helpful diagram and some instructional [...]
Jun 5, 2007 at 1:41 pm rating: +1
#22
Sharkie
This is the best post on this site!
Jun 8, 2007 at 12:28 pm rating: 0
#23
Kelvin’s Second Law of Thermodynamics Explained « alastair’s heart monitor
[...] http://www.passiveaggressivenotes.com/2007/06/03/when-phds-get-frustrated/ [...]
Jun 16, 2007 at 4:47 am rating: 0
#24
Velly
The hot air probably _would_ travel in direction of the open window because the temperature inside the room would be cooler than the temperature outside. Heat always moves to achieve equilibrium — to eliminate “cold”.
Jun 26, 2007 at 3:39 pm rating: +2
#25
Matthew
Neat, cool lesson.
Jun 26, 2007 at 4:12 pm rating: 0
#26
Chak
You dont need a PhD to explain that, a B.S. (bullsh*t) degree would do just fine :P.
He also completely ignored the fundamental fact that hot air rises. I’d question where he got his PhD from.
Jun 26, 2007 at 7:03 pm rating: +1
#27
msquared
Ph.D = piled higher and deeper
Jun 26, 2007 at 7:27 pm rating: 0
#28
ned
copied almost word for word from the howstuffworks.com air conditioning article.
Jun 27, 2007 at 2:07 am rating: 0
#29
Marc
I do not see this as a passive-aggressive note. He may or may not be 100% correct, but he follows a logical reasoning and makes fair efforts to convince the reader to reach the same conclusion, he’s just being assertive which is completely OK.
Jun 27, 2007 at 4:58 am rating: 0
#30
Webmaster X
“Michael // Jun 4, 2007 at 12:03 pm
The room won’t necessarily get hotter. If the cold air blown into the room minus the hot air generated by inefficiencies in the unit is greater than zero then you have a net decline in heat. It doesn’t matter that the A/C blows hot air outside because that shouldn’t effect the temperature inside. It could make a difference if there’s a constant draft going into the room that draws all the heat from the unit in with it but that probably doesn’t happen too often. It still wastes a lot of electricity though. Blowing a fan over a bucket of cold tap water would be a lot more efficient.”
Boy you sure don’t have a fucking clue what you are talkingabout.
Jun 27, 2007 at 5:17 am rating: 0
#31
Rickyp
Why is this by a Ph.D.? Anyone who has taken an undergrad course in thermodynamics would understand this principle. I would be inclined to say that no engineer with a Ph.D. would be doing justice to his argument without mentioning entropy. The net increase in entropy makes the process irreversible and thus a greater quantity of energy than that which is removed from the air entering the room is released into the atmosphere, meaning that if that exhausted air were to enter the room, the total energy in the room would increase. As far as the hot air falling thing is concerned, the difference in pressure between inside and outside is what controls the movement of air more than convection in an open system like this. If the inside is cooler, then there will be a pressure drop outward through the window and the air will tend to flow outward, expelling cold air and replacing it with whatever is in the hallway or reaching a dynamic equilibrium with the outside. Alternately, if it tends to be warmer inside then the air from outside will be sucked inside by the pressure difference, pulling in the hot exhaust and lowering the pressure further and pulling in more hot exhaust until the room is the same temperature as the hot exhaust. Buildings are normally not warmer than the atmosphere (unless it’s a greenhouse or a sauna). Thus, even with the window open one needs not worry too much about the exhaust, that is unless the prevailing winds blow air into the building or perhaps if the wind creates a vacuum on another face of the building (wind blowing perpendicular to a wall with a number of open windows). In general, with such a large system, convection has nothing to do with how the heat flows. But again, I doubt this was a Ph.D., since there is no mention of entropy, and anyone who knew a lot about how heat pumps work (at least anyone who has completed at least a year and a half of chemical engineering coursework) would not be doing the argument justice without mentioning entropy.
Jun 27, 2007 at 5:40 am rating: +1
#32
SirOJ
@Rickyp… you’re an ass… nobody cares you know.
Ned was spot on: copied form howstuffworks.com
Jun 27, 2007 at 5:54 am rating: 0
#33
Levi
Rickyp is not an ass; he’s clarifying for a lot of the people here who seem to have stopped thinking about science in elementary school. “What an idiot, hot air rises man!!!!” . . .
Another ironic thing is that people here seem to be anti-knowledge, as if they are the hall monitors for the school of dunces. First the note was attacked and now Rickyp. Perhaps the world would be a better place if more people sought understanding of and explanations for things instead of taking things straight from the horse’s mouth.
Jun 27, 2007 at 8:42 am rating: +5
#34
Fuck You
Dear asses:
The request is perfectly reasonable. PhD students’ time is cheap because society does not value original thought and the wages reflect this.
Hot air gets sucked into a vacuum, whether it is a literal vacuum (pressure out of equilibrium) or a figurative vacuum (order tends to disorder, as we all observe daily).
Whoever is running A/C with a window open would probably fit right in with the comments. How fucking stupid do you have to be to do this? It’s like trying to carry water in a sieve.
Please do your part to control the population explosion, and kill yourself. Thanks!
Jun 27, 2007 at 8:54 am rating: +2
#35
me
Anhoni: all you had to say was nothing.
Jun 27, 2007 at 9:32 am rating: 0
#36
Mantra
Sound like any engineer. Most PhD’s aren’t that practical - even the one’s in engineering. As an engineer, believe me, dealing with numerically and scientifically illiterate (90% of US population) is very trying at times.
Just yesterday they had Fox news on in the customer cafeteria I was visiting and the dorkbot on the show was looking at a straw poll of Hillary-vs.-McCain which stated that 46% Hillary - 43% McCain with 8% margin of error, and yet the idiot was claiming conclusions from the numbers. Don’t worry I won’t derive confidence intervals and random chance, but the numbers made it self-evident that nothing at all could be concluded. Anyone with a high school diploma should have got that. News is about things that rarely happen - most of the time there is no news. It’s a bad business model which is why we have infotainment instead.
Jun 27, 2007 at 10:03 am rating: +2
#37
anonymoustroll
Someone should remind the good doctor that PhDs are very similar to air conditioners running next to a open windows.
Jun 27, 2007 at 11:05 am rating: +1
#38
Science Humor » PhD pi***d Of*
[...] Please do not run the air conditioner with the window open! (click to see complete) [...]
Jun 27, 2007 at 12:29 pm rating: 0
#39
Bulbboy
Is this why politicians who blow hot air all the time are ineffective when speaking outside?
Jun 27, 2007 at 5:56 pm rating: 0
#40
xian
Most of these notes, while funny, are not passive-aggressive, unless we are redefining the term (see also ‘ironic’), but to mean… what?
Jun 27, 2007 at 11:50 pm rating: 0
#41
LK
i think this note is passive aggressive. the guy went into a completely unnecessary explanation with a completely unnecessary diagram, hinting that he thinks (sarcastically or not) that his roommate is extremely stupid. i think this makes it PA. if he had just said “hey don’t run the AC with the window open” then it certainly wouldn’t have been PA.
Jun 29, 2007 at 6:18 pm rating: 0
#42
conformist_panda
Writing: “Please do not run the air conditioner with the window open. You are killing the planet! (plus God kills a kitten.)” would be better, don’t ya think?
Jun 29, 2007 at 7:32 pm