Cool Definition and 285 Threads

I found this optical illusion today on the internet. This posting is accompanied by an explanation of how it works, that invokes lateral inhibition among neurons in the visual system. There is another version of this available on the internet where they show two versions. one version has red...

Nice improvements in Medic care on the battlefield... Will be nice when it filters down to us in civilian EMS. :smile: Go PJs! http://www.popularmechanics.com/military/a24806/air-force-pararescuemen-medic-of-the-modern-battlefield/

If I have a steady supply of isothermally compressed air at 7 psi (approximately 148 kPa) at a temperature of 4 degrees C, how would I calculate the amount needed of that air per unit time to maintain the temperature of a 14 cf refrigerator at 3 degrees C? A 18 cf freezer at -18 degrees C?

What are black holes made of?

I was wondering how can a gas be a gas but at the same time be cold? I thought gas molecules moved faster than liquid ones do, and yet some gasses are cooler than some liquids. I thought kinetic energy averages dictated temperature??

So I have working code of a : FFT Digital low pass and high pass filter and sound generator What cool projects can I make which these ?

Given a lot of room, talking hundreds of feet of piping, and potentially hundreds of square meters for equipment, how fast can you drop an input ranging from 50-100C down to 5-10C? It can also be partially underground (shallow). In this case, I could use the waste heat, especially if it's in a...

Just Qualitative Analysis: There are many ways of cooling a coffee cup. But here I want to understand about concept of fins. So I am using a spoon to enhance the heat transfer rate. Put the spoon vertically in the cup. We have two ways to put the spoon, other one is upside down. I am curious to...

APPLICATIONS OF CLASSICAL PHYSICS 2012-2013 Version of Textbook by Roger D. Blandford and Kip S. Thorne http://www.pmaweb.caltech.edu/Courses/ph136/yr2012/ I believe this is a precursor to the following textbook (yet to be released) https://www.amazon.com/dp/0691159025/?tag=pfamazon01-20

Hello, I am looking for an "easy" but cool electrical engineering project. I've tried to make a mini tesla coil, but I keep messing up the coil part itself, so I am taking a step back from it for a while. Are there any relatively easy (I am beginning) electrical projects that you have heard of...

Hi everyone. I'm not sure if this should fall under Biology and Medical, or under some other science category, but I found the following news link from the Santa Fe Institute (SFI) website, about analysis by physicist and complex systems researcher David Wolpert, which suggest that imprecise...

Hello Everyone! My name's Christina and I work at the Everyman Theatre in Liverpool... We have a show coming up in the main space at the beginning of July that's going to be performed by YEP (Young Everyman and Playhouse)... and hopefully it's going to be a love story about all things Physics-y...

Hi all! I have recently taught myself parametrics, and I stumbled upon the butterfly curve. So, I was wondering about some cool equations I can plug into a parametric graphing calculator.

Can someone explain how this happens?

I need a way to generate cool air outside when temperatures are 90s and above. Basically what I am thinking of doing is essentially like positioning a fan right beside a bowl of ice cubes. Only in my case, instead of using ice cubes, an electrically powered cooling device that can slightly...

Hi, my name is Noel, i am currently a final year student , in newcastle university majoring in offshore engineering! i love to play dota, going out to watch movies, listening to musics and love reading book. I hope to make many like minded friends through this forums and finally NICE TO MEET YOU!

I've just read about the second sound and that this phenomenon can be seen in superfluid 3He at 2.5 mK. How do they manage to come that close to 0? A short hint about the methods would be nice to read. Normally you hear that things are cooled by fluid nitrogen or helium. But mK are out of...

What are some cool things that people can do with the Pythagorean Theorem?

According to standard cosmology theory the physical momentum p of both massive and massless particles decay like: $$p \propto \frac{1}{a(t)}$$ where a(t) is the scale factor as function of cosmological time t (for a derivation see page 12 in the following lecture notes...

Homework Statement [/B] If you had a water-cooled computer that puts out 500W of heat into the loop with a large copper 100 liter reservoir but no radiators, how long can you keep the temperature of the components below 70 degrees Celsius if the initial water and air temperature is 20 degrees...

I found a really cool website where you can have physics problem solving competitions with others. It's brand new and it's called PhyKings: www.phykings.com. You can start a competition, pick the number of players, the length of the problem, the type of problem, and once everyone joins, you...

Hello, I have six 1*2*0.5 rectangle neodymium magnets. I don't know what to make with it so are there any suggestions? I want to make a machine or something that can move, however, I don't know much so any idea will be appreciated. Thanks!

Homework Statement A student is calculating the resistance of a piece of fuse wire. He takes 5 readings on the voltmeter and ammeter for different settings of a variable resistor. He wants to avoid heating effects in the wire. How would he do this? Homework Equations V=IR The Attempt at a...

Hi guys, I have a question on cooling the house. So at night, I usually open windows to let all of the cold air come in and open the 2nd floor windows to let the hot air out. The 2nd floor is a large open area and has windows in the front and windows in the back. Now, I normally open all the...

Can we use fast-growing sea plant to increase the surface area of the sea, enhance global evaporation, and get the Earth cooler? Do we know some sea plants growing really fast with photosynthesis? I was struck with this idea when I was doing a search on giant vegetables on land.

What courses or physics topics would you like to see on the internet? I want to make a physics course series. I want to make videos and other resources (like animations, simulations apps, and games). I want it to be on topics that don't have a lot of videos and resources, and there are people...

Question: What parameters are needed to have no slippage between 2 small drive wheels and the bowl? Startup of the system is obviously the moment where there is the greatest chance of slippage. As in the illustration above this is a possible layout of a device for rotating a large bowl...

An interesting article on an elliptical pool table along with the math to understanding how to play on it and the physics which alters game play. http://www.theguardian.com/science/alexs-adventures-in-numberland/2015/jul/16/loop-new-cue-sport-pool-ellipse-elliptical

I read an article a day or so ago titled Hydrostatic Lapse, which makes the case for a phenomenon that I thought was well and truly confirmed; that gravity is responsible for the cooling of air with altitude. However I discover in the sequel article The Gemini Cycle that this phenomenon is...

And does it matter if you are going from 200F to 100F or 500F to 400F? ie, is it temperature dependent?Thanks

From things I've read it states that water oozes through pores of clay pot to outer surface and absorbs the heat form outer air.The heat absorbed is latent heat for water and specific heat for air outside which lowers the air temperature and as evaporation on outer surface takes place water...

I just sat with a cup of tea, and started wondering about this. If the cup just sits there, the tea will cool slowly. Will it cool faster if I repeatedly clench and let go of the cup? The difference between the cup surface temp and the surrounding air is higher than than between the cup and my...

I thought this was a super cool vector, example problem from An Introduction to Classical Mechanic by K&K. It says: The solution first begins by recognizing that since the problem is asking to find a unit vector perpendicular to A, then we can conversely say that the dot product of A and B must...

Just wondering If it is possible to laser cool an object from afar or from a large distance away? Suppose you wanted to laser cool a planet with satellites in orbit around it, Would that be possible? Doesn't matter If they'd have to be ridiculously huge to have a noticeable effect or would take...

If Wikipedia were a galaxy and each article a star Each section a planet leaving each word to remind us Remind us who we are. http://phys.org/news/2014-12-wikigalaxy-wikipedia-galaxy-stars.html

*Looking for cool ideas for a Bachelor project!* Hi everyone! We are a group of 4 mechanical engineering students that will be doing a Bachelor project for a local hydraulic-systems company. We are just thinking of/looking for ideas...it will not be produced so cost is not a concern. Pretty...

I'm aware that it helps keep warm things warm—but does it similarly help keep cool things cool?

In "Loop quantum gravity and observations" by A. Barrau and J. Grain at http://arxiv.org/abs/1410.1714 the bottom line seems to be that the phenomenological implications of LQG relative to existing predictions from GR are so extremely subtle that they have virtually no practical effects that can...

Hi, I am a non technical person seeking some advise from experts. My question is like this - I get bread from the machine at 30 Deg. Celcius and store it at warehouse maintained at 25 Deg. Celcius along with some other bakery products. Our ware house has capacity to maintain 25 Deg. Celcius...

I just discovered VimFx extension for Firefox: it installs some Vim-like keybindings for Firefox. Unfortunately, you don't get Vim keybindings for text boxes such as the one I'm in now. But you do get some very nice keyboard-only shortcuts for browsing that make sense to a Vim user. If you're...

If heat is motion, why do fans cool you off? My guess is that if you had a closed room (so no air goes in or out, but obviously energy would be coming in from the fan) then the fan actually would heat up the room on average. My guess is that fans only create some kind of apparent coolness...

Hello, Can someone please explain to me how Astronauts in Low Earth Orbit do not instantly fry up when in direct sunlight? How does the International Space station, for example, not become a torch-lit super-oven when the sun's rays hit its walls? Thank you for helping me understand, and...

By a fortuitous mistake in copy/pasting, I happened across this system. It exhibits very chaotic behavior for some initial values and spiral-like shapes for others. (About a 70%/30% split, respectively.) x'=cosy+sint y'=sinx+cost Here's an album of it plotted from t=0 to 1000. The titles of...

Anybody think this identity is not super-cool? \begin{eqnarray} \frac {1} {1-x} = (1+x) \prod_{n=1} ^{\infty} [ \frac {(1+x^{2^n})} {(1-x^{2^n})} ]^{2^{-n}} , {\;} for {\;} 0{\le}x<1 \nonumber \end{eqnarray}

Hello, I am looking for a physics/engineering project that is doable over a couple of weeks and has a bit of wow factor. Building a trebuchet would be a good example but I would like to do something else. Any ideas? Thanks.

http://www.youtube.com/watch?v=fhLfLOcRHlw&feature=player_detailpage#t=961 I linked the time already for you, feel free to watch the whole video though if you want.

example: 1+(1/2)+2+(1/4)+4+(1/8)+8+... = 0 What does this imply?

I'm well aware that the default answer to this textbook default question is "it doesn't work", but still, I believe it does. To cool the insides of the refrigerator, the compressor must do work, and since the efficiency isn't 100% you are constantly warming the whole room to cool it's...

Hello people, thanks for reading. I am glad you are checking out my problem. Basically I need to confirm a "theory/formula" that my boss had written down from a decade ago declaring how much water (roughly) would be needed to cool Slag from steel making process to below boiling. PROBLEM...

Hello all, thanks for reading. I am trying to figure out how much water (gallons) would be needed to cool 1 ton of molten Carbon Steel from 2200F to 212F. The specific heat of Carbon Steel is 0.49 Kj/kg.C I am not sure where to start. I tried used Newtons Law of Cooling but I don't...