Hot Definition and 549 Threads

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...

i think that the reason of hot water 'float' on the cold water is not because 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

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?

If you had 2 identical stars, one was a very hot star, but the other was cooler. Since mass is relative to velocity, shouldn't the hotter star be more massive than the cooler one since the atoms in the hotter star would have more kinetic energy and therefore a higher speed?

Why does hot air rise? What I'm really getting at is why should the speed of kinetic motion of the individual atoms of heated air rise compared to it's slow moving neighbor, is it merely because it bounces around more often and so all air competes for dominance upward such that the fastest...

I have a question for you all, say you have a pressurized cylinder with water in it, it is at 200*F and at a pressure of 300psig. Now you open a drain valve on the bottom to the atomosphere. Will it flash to stream or just come out as hot water or a combo of the two? What equations and...

CAn you tell me why will the temperature of the surface will be hotter at the top on the blub rathen than on the side? thank you

If scientists understand hot and cold completely then high temperature superconductivity will become a reality and cold fusion is just child play. Until then, we can do all the theorizing we want but to really understand the universe we must understand what is hotness and what is coldness...

I'm eating some chinese food now. About 2 minutes ago it was hot and tasted good, now it's just kind of warm and isn't as appealing. Why is that?

I have heard this argument all my life. Some say put hot water in an ice tray and it will freeze quicker than cool water. I don't follow the logic to that way of thinking. Do you? What is the right answer?

There is this very tasty Vietnamese soup, which is on the top of my favorites list.. I once made it myself by just putting together the ingredients which I noted in the restaurant.. and it tasted pretty amazing I must say I'd really like to know the original recipe though, anyone an idea...

There was no mention of Moon bases and Men on Mars in his SOU address last night, or at least according to the review I listened to (BBC?). Is this good news?

http://www.sfgate.com/cgi-bin/article.cgi?file=/chronicle/archive/2004/01/19/MNG3G4CAMF1.DTL

This is my first post and I’ve got some questions in regards to our universe. From what I’ve been reading it is known that the universe began in a hot big bang, or evolved from a similar condition. Either way the information we have points to some kind of initial condition, and also a beginning...

Another "new" release from NASA. Just click to join and you'll get these every day. So, I won't post these anymore. This subject has been discussed here on PF before, but this release should answer some of the questions asked...

Hypothetical experiment: I have a single 2-inch by 2-inch by 1-inch thick Neodymium magnet affixed on the outer rim of a 1-foot diameter circular hard plastic disk(1/8th-inch). The disk and magnet are held stationary by whatever means. The underside of the plastic disk has a coating, an...

Who can tell me some typical topics in Condensed Matter Physics nowadays?[?]

Hello all, It's time for a little experiment. As part of my constant quest to stimulate discussion and bring more technical content to physicsforums.com, I am going to occassionally provide links to posts from the usenet newsgroup sci.physics.research, which is a moderated internet-based...

http://www.sptimes.com/2003/10/05/Tampabay/Hot_Psychology.shtml

i have heard that there exists an anomaly in amount of neutrinos coming from sun. are there any explanations around? how is the presence of Jupiter sized planets near stars have been explained?

It's a question that boggles the mind. If you answer yes, than God could not eat that burrito, meaning he is not all powerfull. If you give a negative response, you are limiting God's power by saying that he can't make that burrito. Either way you end up with counterevidence to God's existence...

why is the core of our Earth so hot? what causes it to be so? and why some other stars and planets like neptune/uranus (i forgot) does no have such a hot core? and what purpose does the molten core of our Earth serve?

Is ethidium bromide volatile in hot agarose solution? Some people add ethidium bromide to melted agarose solution, or reuse agarose containing ethidium bromide by melting it. If EtBr is heat-volatile, then it may pose danger to these persons. I always feel uncomfortable when remelting gels and...