Hot Definition and 572 Threads

Please help me with this : 1) Water circulates throughout a house in a hotwater heating system. The water is pumped at a speed of .7 m/s through a 4 cm diameter pipe in the basement under a pressure of 3 atm. What is the pressure, to the nearest N/m^2, in a 2 cm pipe on the second floor 5...

I know a hot air balloon goes up because the density of the hot air inside is lower. But what about free air, not trapped in a balloon? You often see exactly the same explanation, hot air is less dense so it goes up, but this does not make any sense if you consider the fact that air is just a...

Homework Statement A hot body is brought into contact with a colder body until their temperatures are the same. Assume that no other bodies are around. 1.Is the heat lost by one body equal to the hear gained by the other? 2.Is the temp drop of one body equal to the temp increase of the...

Hi there, I have a tiny 48-QFN chip that I have to solder manually. The pin width of the chip is .28mm and the clearance of the pins is .22mm. The pins are totally under the chip and from side I can only see little metal indicating the positions of the pins, which makes it impossible to...

What are average high temperatures in the middle of the deserts during hot summer times? A sattelite has recorded a surface temperature of 71 Celcius (159 F) in Lut Desert in 2005, however no given date or season in 2005. How about temperatures above 1,5 m from the ground and in other hot...

So I have an LC circuit at resonance except the capacitor gets very hot. There is about ~2Amps AC going across it. The setup is: 2x 0.1uF capacitors in parallel ~304uH inductor the ESR of the cap is 0.56ohms and the resistance of the inductor is ~0.7ohms. I was looking for the...

There are situations when a water drop falls on a really hot metal surface and, instead of evaporating, it kinda bounces on the surface. Why?

Hello there! It's been about a grillion degrees up here in my home town recently and last night this led me to a sort of conundrum. If I open the window in my room but leave my door shut, hardly any air comes it at all. If I open my door, there's a strong puff of wind that comes into the room...

Hey there. So we have an old home (1902) that is 3 stories. We currently have a tenant in our ground floor apartment. She just informed me that she is unable to get the hot water to come out of the bathroom sink tap. She could let it run and run and it will not get hot at the sink tap. Her...

What is the reason for paper getting stuck to a hot bowl when it is kept on paper for a certain period . I hve seen particularly that newspaper when placed under a hot bowl gets stuck to the bottom of bowl when the bowl is lifted ? I think the cohesive forces b/w the the two surfaces must...

Hi everyone I work for a very small company, which produces steel products. Predominately from one particular hot rolled steel profile. (1040 grade) We currently subcontract our hot rolling to small chinese operators :( I know... At this stage our volumes are not large enough to warrant...

lets say we have to functions y(x) and g(x), how would I determine in which interval y(x) would be greater then g(x)? Would i simply subtract them and determine where the function is greater then zero (this seems to make the most sense) But I also remember that if I subtract them and take...

Hot ice solidifies instantaneously when its cold... http://www.youtube.com/v/aC-KOYQsIvU Are there really any oscillations or waves of different states (alternating states) in materials? Perhaps gradient of heat or a bump of pressure spreading? Sound? Electricity?

(Hot here refers to temperature, NOT the obvious radioactivity),Yes, perhaps a silly question, but maybe not. I can't remember where I read about Russian children finding "radioactive" metal in a forest that had melted the snow around it. Perhaps they found metal that had been neutron...

Hot, Sexy Physicists... I don't know why but I think that John Hagelin (prepped at Choate Rosemary Hall, Dartmouth undergrad, Harvard PHD, post grad work at CERN) is all that and a bag of chips! And he looks so different than shall we say a "random sample" of the writer's previous gentleman...

help Calculus! Homework Statement got this question, and i need help. lost it lol. this is the sort of question i have to do for me assignment. Help in going through it Homework Equations Hot metal storage tank: is rectangle with a square cross section total surface area is...

[see attached diagram]I've not yet tested this! Trying to find portable instant hot water systems on line, I thought of this: A thin copper tube coil cone that can be placed over a conventional gas cooker burner. The cold water source can be a tap(faucet), raised storage container, or a pump...

http://www.cbsnews.com/video/watch/?id=4955212n So, what should one make of this? I would love to hear what people here with physics know-how think about both the people and the experiments. k

Okay so i have a project, and this is pretty basic physics but I'm kind of confused. so for those of you how a turbo work, please help me out here. okay so: pV = nKT in thermodynamics. so in a turbo, as air enters the compressor turbine, n and k stay constant correct? however as air enters the...

I know that the mantel of the Earth is kept hot by radioactivity, but is this also true for the core?

How "hot" of an area of research is particle physics? Hello friends. I am currently trying to decide which branch of physics I want to go into. I have been interested in working as a theorist in particle physics, but I am afraid that the job market for this is not good. Also, I am afraid that...

This isn't really in the usual thread of these forums but physics is what I need to provide the answers and I don't have a good enough grounding in the topic. Here is my problem: I have a storeroom that is about 5 x 2.5 x 4 m. At night it is locked up for around 12 hours duration. Inside...

Is it possible to neutralize the chlorine in a hot tub before using it? I figure if you can sanitize the water after using it and then neutralize it before using it, your skin wouldn't be absorbing all the harmful chemicals. I love my tub, but don't like soaking in the hot chlorine water with...

If their was a suit that was able to stay hot on the outside of it, and you had no choice but to jump off an airplace that was about to crash and you were flying over the ocean. Would you be safe to jump into the ocean without breaking anybones because this suit was able to stay hot. I think...

1. A hot-air balloon is ascending at the rate of 11 m/s and is 53 m above the ground when a package is dropped over the side. (a) How long does the package take to reach the ground? (b) With what speed does it hit the ground? 2. v = u + at s = ut + 1/2 a t^2 v^2 = u^2 + 2as 3. s...

Hello, I'm working on material transfer during hot working. My chemistry isn't to good. Could anyone explain if different oxides give different properties to different materials. Say MgO, would it give a different property to Aluminium from that it would give say Steel? If so is there...

I am trying to get a close look at magnetic nanoparticles under a relatively strong microscope (600 times plus). I am trying to observe their behaviour when an alternating magnetic field is applied. The problem is the alternating magnetic field heats up all metal in its surroundings...

Man, its the middle of january, and I STILL can't turn my A/C off! It's so hot and muggy, I almost miss the cold. I guess that's New Orleans fer ya' Anyone else from the big easy?

How would you find fnet if there is no force applied? does anything happen to the other forces as well? how do you find the theoretical and actual distances traveled up and down an incline if you have photogate data and need to find the theoretical and actual distance traveled? should i...

If a hot metal forging is cooled by dropping it into a pool of water, how many boundary/initial conditions do I need to solve for the temperature? I don't want to make any assumptions about temperature gradients within the forging itself (Biot number may be large, which precludes use of lumped...

Homework Statement In a well-insulated calorimeter, 1.0 kg of water at 20o C is mixed with 1.0 g of ice at 0o C. What is the net change in entropy Delta Ssys of the system from the time of mixing until the moment the ice completely melts? The heat of fusion of ice is Lf=3.34x105 J/kg. Note...

People often explain this by saying that dark colours are good absorbers of radiation (compared to white). But in itself this explanation is not sufficient; a good absorber of radiation is (by definition) also a good emitter of radiation! Does the dark T shirt enable your body to reach...

1.Hi, I need to create a scale drawing of a hot air balloon at which we are creating, it is odd because I don't know how big it's going to be and have no idea how to make a scale drawing, the balloon does not need a basket but will have mints attached to it (as passengers) to see if it can hold...

Homework Statement Put a hot metal ball on parallel horizontal rails. The ball starts to move. Investigate the phenomenon. Homework Equations I have found two equations, one exponential and one linear relating the expansion of the rails and the ball to the temperature increase...

Hello everyone, I'm supposed to start my PhD in Biophysics. and I just need help and suggestions about what are the hot topics and issues in Biophysics. I don't want to do something, and end up after 10 years alone in my desk and am the only one in the world doing it. So, can anyone...

Physics problem...! A hot air balloon is ascending straight up at a constant speed of 7.50 m/s. When the balloon is 15.0 m above the ground, a gun fires a pellet straight up from ground level with an initial speed of 38.0 m/s. Along the paths of the balloon and the pellet, there are two places...

Homework Statement A physics student in a hot air balloon ascends vertically at a constant speed. Consider the following four forces. that arise in this question. F1 = the weight of the hot air balloon F2 = the weight of the student F3 = the force of the student pulling on the earth F4...

Hi, I was just wondering, if you say "The temperature today was twice as hot as it was yesterday", in which units are people usually referring? Degrees Celsius doesn't make any sense, since it is perfectly possible for something to be twice as hot or cold as 0C... For the same reason I don't...

URGENT: Why do you feel hot after you work out? Why do you feel hot after you work out? Explain using concepts of cellular respiration.?

Homework Statement A 900 g aluminum pan is removed from the stove and plunged into a sink filled with 12.0 L of water at 19.0 degrees. The water temperature quickly rises to 24.5 degrees. What was the initial temperature of the pan in degrees C? What was the initial temperature of the...

Homework Statement A 150 g copper bowl contains 220 g of water, both at 20C. A very hot 300 g copper cylinder is dropped into the water, causing the water to boil, with 5.00 g being converted to steam. The final temperature of the system is 100C. Neglect energy transfers with the environment...

How does a DMM read the Hz of two hot legs, like in a 240v recep? It looks like it only reads one phase

The big bang is defined as the theory that the universe has expanded from a primordial hot and dense initial condition. Was it hot? I would suspect that the initial condition was in fact cold due to the lack of space and therefore movement. The heat happen directly after the bang. Does this seem...

As the thread title suggests, I have some "hot pink" undies: they're closer to red... really :blushing: Anyway, I am a little worried about washing them. The tag says to wash them on Hot, which is fine, but I'm not sure what other clothes to put in the washer with them. My concern is that...

Homework Statement Hello all, I am having trouble with the following homework question using trigonometric formulas and the Sine Law. Here is the problem: Jack spotted a hot air balloon from his house at angle of elevation 57 degrees. Jack's friend who lives 26 km from Jack's house spotted...

I understand that vasodilation occurs when it is hot (to evolve heat away) and vasoconstriction when its cold (to retain heat) 1) What is the mechanism through which heat causes vasodilation? 2) How hot is our blood (temperature). Is it hotter than 98.2 F because of glycolysis? Thanks

Is the temperature of Venus's atmosphere due solely (or primarily) to its density? What would happen if the sun's light could be blocked from its surface, would the atmosphere eventually freeze? If so, how long would it take?

A friend of mine told me this; you take a metal pole or rod and hold on to one end while warming up the other until it's red hot. Then you stick the warm end into cold water. One would expect it to cool down, and it does, but what happens is the end you're holding on to very quickly gets so hot...

Temperature: Does it make sense to say something is "twice as cold". (or hot)? Here's an old joke: If the temperature outside is zero degrees, and if it will be twice as cold tomorrow, what will the temperature be? The joke doesn't specify if the temperature is given in degrees Fahrenheit...

I liked the "most useful 4yrs degree" and want to get a similar discussion started on industries. Let's hear what careers fields you think are going to grow in the next 10 years. Here's my list (easy list): Healthcare: Population grows and new diseases appear. Nurses, doctors, EMTs...