Hot Definition and 572 Threads

I usually use an average number of 2 kPa friction loss for normal tap water in pipes. Does anyone know if this number changes significantly up or down for water which is around 80 degrees C instead of 5?

Direction of heat? "Hot to cold..." Please explain. During a college prep class last year, my physics teacher said something about the direction of heat. He asked a student, "Which direction does heat go? From hot to cold, or cold to hot?" I'm pretty sure that's what he asked. I wish I had...

http://arxiv.org/abs/astro-ph/0505036 http://www.universetoday.com/2006/06/12/gigantic-ball-of-fire-discovered/ the popular news item says "gigantic-ball-of-fire-discovered" heh heh it is a gas cloud in the cluster Abell 3266 which is hot enough to be observed in Xray wavelengths----ie...

Is it true that if you take the same food, same amount and everything except one serving is heated and another is not. Would the person eating the heated serving get more nutritional value from it in the form of more energy? This comes about from the larger potential energy stored in the bonds...

Recipe: -First, heat up your pants really hot, then add oil. -Put the cabbages in salt water. Then sit in the sink until the morning. -Next, chop all the vegetarians into little pieces. -Next, add a little Buddha and mix it all up. -When you are finished cooking, find a suitable bowel...

What do you think the hot topics in maths will be in the future? I can only speak from an applied point of view, but perhaps someone else could come in from the pure angle... In the 90s, I think the hot topic was ''Chaos Theory'' ( http://en.wikipedia.org/wiki/Chaos_theory ) - even banded...

Hey so I am stuck on a 2part question, it goes as follows: A tungstan filament in a light bulb is rated 75w for a 230v supply. The resistance of the filament at 20*C (*C means degrees celcius) is 68 ohm. Assume a constant temperature coefficient of 0.005. Calculate: A) The hot resistance...

This was a question posed to me by a homeowner. I don't know very much thermodynamics and hope someone here might have a better understanding. They have a run of 3/8in copper pipe leading from their water heater to various taps. On cold mornings, it takes a long time, for hot water to flow to...

Consider a spherical hot body having a temperature T, located on one of the pans of a very sensitive balance. It is equilibrated puting a given mass on the other pan of the balance. The temperature T is lower then the ambiental one. The balance is in mechanical equilibrium but out of thermal...

A thing i have noticed when burning paper on an open fire, the paper has burnt, and left a carbonized sheet, every so often a red hot thin thread travels along it, even on a very hot roaring fire the sheet will stay intact for several minutes, but what are these red hot threads burning.

A spoonful of sugar is dissolving in hot water. The initial mass of the sugar was 7 grams and 5 minutes later the mass present had halved. The mass of sugar, S grams, at time t minutes after it was placed in the hot water can be modeled by S(t) = S0e^−kt, t ≥ 0. b Find the exact value of k...

This subject came up in HRW's thread about dating, but I didn't want to drag it off-topic. The question is, what do you mean when you use the words in the subject heading, specifically when in reference to someone of sexual potential? This topic seems to have come up in conversation with...

So I was wondering (after laughing at a hilarious Seinfeld episode as usual) something, why does spicy food make people sweat? Also, why do some foods seemingly set off a bomb in your sinuses and clear them out pretty dang well? I've had chicken that was about 100x more effective then any cold...

Hi I have a toshiba laptop, xp, and have a problem with the keyboard freezing up. When this happens there seems to be no response to any keyboard or mouse command. The only fix I have found is to shut the computer off and then reboot, after which everything seems fine until the next time...

I have a question about the hot death model of the end of the universe. If the current expansion of the universes was to slow down and eventually the universe started to contract ( I know very unlikely but…) would the matter in the universe coalesce into black holes, before the temperature...

Hello, my colleague told me that he read once somewhere that water freezes more quickly if it is given to frost hot. It is supposed to be caused by tighter organisation of moleculs in a hot water and thus being better prepared for transition into crystalic state of matter. Is there any...

Google scholar has 651,000 results for dark matter and 521,000 results for dark energy, more than i could read in a life time, can anyone suggest the hot pappers on these subjects.

Hi, I'm not sure if this is in the right section but here it goes. Ok for the sake of this question let's assume that the water hasn't run for a few hours Whenever I first turn on the hot water, the water first runs either cold or room temperature (depending on the amount of time since the...

1st year physics help - hot air balloons... see next post...

hot metal + water = Tf? Yet again I find i am stumped by having no clue as to what I did in this incredibly easy problem. Simple right? 1 = water 2 = copper m1c1 delta T1 = -m2c2 delta T2 This simplifies to... m1= (-m2c2 delta T2)/(c1 delta T1) which is...

My kitten Salem, who is almost a year old now, is a vocal outdoor cat. An she loves to be petted. Especially when you pat her head and her ears. One thing I contimually notice is her ears are hot to the touch. I don't know if its normal or not. Does anyone know anything about this? ~Kitty

Hi, recently I found something out by playing around with candles. Basically I heated some candle wax until it was completely out of its solid state (at least through the first approximation of my eye.) Then I continued to heat the wax until the liquid wax ignited and started to burn. Usually...

They haven't figured out what is causing these anomalous hot spots near Santa Barbara: Earthfiles.com Address:http://www.earthfiles.com/news/news.cfm?ID=938&category=Environment

Reaaaaaaly hot weather... I just checked the http://www.crh.noaa.gov/forecasts/PAZ068.php?warncounty=PAC091&city=Norristown for tonight (pic attached for if the link has been fixed). Good thing I have air conditioning.

While in a car on a hot day, I notice that far ahead of me is a mirror-like surface on the road. I can see the reflections in that virtual mirror too. The mirror shifts with your moving forwards. Can anyone give a simple explanation? Thanks.

Hi. There is a hot air balloon with total mass M. There is an upward lift force of 2Mg/3 but the balloon is accelerating downward at a rate of g/3. The passenger needs to make the balloon lighter and starts throwing things of. What fraction of the total weight must he drop overboard so that the...

>today while drinking coffe at starbucks i meet this hot hot girl,(all dudes were devouring her with their eyes) we talked about stuff, she gave me her e-mail. everything sounds perfect, :frown: unfortunatelly in two days I'm flying 6,000km to my old folks and i will stay with them for about...

i think that the reason of hot water 'float' on the cold water is not becuase of diffrent density. i make a model of a container containing a higher energy particle (hot water) and lower energy particle (cold water) using action script in flash and uploaded it in geocities...

they ran computer simulations of 8500 planetary systems to see how giant planets could sometimes MIGRATE in close to the star and they got some statistics of what one might expect. I cannot vouch for this paper, or say how it stacks up compared with other similar papers, but this business...

A person makes a quantity of iced tea by mixing 559 g of hot tea (essentially water) with an equal mass of ice at its melting point. If the initial hot tea is at a temperature of 94 C, what are the (a) final temperature of the ice tea (in oC) and (b) mass of the remaining ice? what are the (c)...

I'm confused as to what equation I need to use for the following problem: A hot-air balloon achieves its buoyant lift by heating the air inside the balloon, which makes it less dense than the air outside. Suppose the volume of a balloon is 1820 m3 and the required lift is 2983 N (weight of...

while measuring th thermal conductivity of water the upper part is kept hot,why is this so? is this so because heat conduction is easier downwards.

Do i need to work on ice when i do Hot start PCR? Hope for inputs. Thanks.

When fuel is burnt in the jet engine, what is the major component of the hot gases thrown out of the back - the CO2 formed (I know CO2 is not the only component but it is the major one) from the fuel or the air entering the jet as a whole? In other words, does the heat of the burning fuel...

Exoplanet statistics have been accumulating since 1995 (and especially since january 1996) the statistics are observationally biased. it is easier to detect hot jupiters. but even allowing for the bias, the picture is very strange massive planets in near circular orbits at...

Can someone help me. The questions are in bold and my anwsers are not. Can someone explain it to me. 1. Why do you feel hot after lifting weight? Does it have something to do with cellular respiration.. 2. Can you tell when your muscles went into anaerobic respiration? What evidence...

A tank in the shape of an inverted right circular cone has height 8 meters and radius 6 meters. It is filled with 7 meters of hot chocolate. Find the work required to empty the tank by pumping the hot chocolate over the top of the tank. Note: the density of hot chocolate is 1510kg/m^3 m =...

I'm studying interference and optics at the moment - can anyone explain why in hot weather dry streets can appear to be wet? Thanks :smile:

I was wondering whether anyone could give me a bit of a point in the right direction for a physics assignment I have been given. The Question is: When a droplet of water or other liquid falls on a hot surface, it produces a sound. On what parameters does the sound depend? Any thoughts...

hot coffee! i went with my friend and his wife to the coffee shop. the coffee was brought when my friend's wife was in the wash room. it was steaming hot while the milk was cold.we mixed the coffee and milk and started drinking. (considering the fact that i prefer my coffee without milk, take...

Could hot dark matter be cold dark matter? In other words did hdm cool and become cdm? And could hdm moving at or close to the speed of light exist beyond the most distant detected galaxies?

A hot air balloon plus cargo has a mass of 291 kg and a volume of 809 m3. The balloon is floating at a constant height of 6.25 m above the ground. The density of the outside air may be assumed to be 1.29 kg/m3. What is the density of the hot air in the balloon? can someone help me with this...

hello, i am a homeschool mom with three inquisitive children. they would love to know why fire is hot...if anyone can answer this question i would appreciate it. i realize that this may be difficult to put in laymans terms, but any information would be helpful... thanks :) ~mbinnc :confused:

http://www.washingtonpost.com/wp-dyn/articles/A55041-2004Oct22.html

Hey you dudes, question to you; how come Asian girls are so hot? I personally love each and everyone of them but the most hottest girls in my view are of mixed race japanese/vietnamese,thai/chinese you catch my drift. So...?

can someone help me with this problem? A hot air balloon has just lifted off and is rising at the constant rate of 2.4 m/s. Suddenly, one of the passengers realizes she has left her camera on the ground. A friend picks it up and tosses it straight upward with an initial speed of 11.2 m/s. If...

can microsoft word or excel set up hot keys for the greek letters(+-) symbol? what about super/sub scripts? can mircosoft or excel do any of that? I am trying to write my physics lab report and i need to input a lot of symbols. if mircsoft word/excel can't do it, is there any program that can? i...

A hot-air balloonist, rising vertically with a constant velocity of magnitude v=5.00m/s , releases a sandbag at an instant when the balloon is a height h=40.0m above the ground . After it is released, the sandbag is in free fall. 1.) Compute the position of the sandbag at a time 0.165s after...

I have just read in a news@nature (http://www.nature.com/news/2004/040726/full/040726-16.html) a column by Phillip Ball on the paper of Sidney Redner (http://xxx.arxiv.org/abs/physics/0407137), who have studied the statistics of citations from all Physical Review journals for the 110-year...

Why is it harder to slow a car down when the brakes are hot? Is there less friction between pads and disc? Is it harder to remove bits of pad material which can carry away kinetic energy?