Heating Definition and 590 Threads

Toasting in a toaster is usually considered cooking by (infra red) radiation. But the hot coils touch the toast so an element of heating by conduction occurs as well. Are they both equally as valid or is one more valid than the other. If the latter than which one and by how much? On the other...

A physicist, upon awaking one morning to find his stove out of order, decides to boil the water for his wife's coffee by shaking it in a thermos flask. Suppose that he uses 380 cm3 of tap water at 58°F, that the water falls 1.15 ft each shake, and that the physicist completes 32 shakes each...

Hi. I'm just curious why did the colour of the heating element of my soldering iron change (see the picture attached). I mean I know it's because of the heating but what exactly makes the colour change? Is it oxide? Or is it because of a change in the crystalline structure of the metal?

Homework Statement its a long story problem so ill break it down: an electric heater generates 250 Watts of electricity, how long will it take for 250 grams of water to heat from 20 C to 80 C The Attempt at a Solution so 80 C - 20 C = 60 C , i have to heat it 60 C 250 grams of water...

Suppose you have a weight hanging from a rubber band and you heat up the rubber band, will the weight go up or down? from grade-school the answer "down" was pounded into my head - obviously - when something is heated it expands! but yesterday i was reading the Feynman lectures and in the...

I have a question regarding plasma .Suppose i heat a certain amount of dioxygen , O2 , which will first easely break into oxygen and after come to a point where at least 1 electrons gets free of the oxygen atom and hence the substence become plasma according to the definition. Now , if i keep...

Hello everyone, new member here:smile:. My sister asked me this today - real-life physics at work! She's making Christmas pud & the instructions say it takes 8 hours to cook. However, her bowls are too small, so she's made two little ones instead, and she asked how long to allow to cook...

Does it sound at all reasonable that a heat-exchanger of 250 kW can heat water from 5 to 55 degrees C for about 120 "normal" appartments directly without any accumulation when probability is taken into account? If not, how many liters should be accumulated?

To what extent is Earth's surface heated by heat from the interior? There were differing opinions in my Astrobiology class today. I would guess that solar radiation is by far the dominant source, perhaps 100:1 vs interior heat. Does anyone else have a better guess, or perhaps a source or...

An electric heating coil is immersed in 4.2 kg of water at 22°C. The coil, which has a resistance of 260 Ω, warms the water to 33°C in 3.5 mins. What is the potential difference at which the coil operates? I was looking through the chapter, and did not see any equations that I can use that...

After heating some glass bottles to a very high temperature with a bonfire the bottles changed shape as you would expect molten glass to do, but once the bottles returned to ambient temperature they were extremely brittle. What is happening to cause this? I read that annealing requires heating...

INTRODUCTION:Here is a problem on "Heating Effect Of Current".I can't understand a part of it. EXACT PROBLEM: "A battery of emf E and internal resistance r is supplying current to an external resistance R.(a)Show that the power dissipated in R will be maximum when R=r.(b)What is the maximum...

Is there a way to measure the temperature in an induction oven for melting of aluminium(700 C). The pyrometer I’m using can’t correctly display the temperature when the system is running because it interferes with the induction field. The non-contact IR-camera has been abandoned because of the...

Sir, Please help me with this problem. A Volume – Temperature diagram was obtained when a gas was heated at a constant pressure. During the heating process from state 1 to state 2 how does its mass vary? Sometimes the diagram may not clear, so I will try to describe how it looks like. It...

2-48) The 60-W fan of a central heating system is to circulate air through the ducts. The analysis of the flow shows that the fan needs to raise the pressure of air by 50Pa to maintain flow. The fan is located in a horizontal flow section where the diameter is 30cm at both inlet and outlet...

We have an electronics enclosure that has a top with 23.3 square feet. It is painted white and I have read that a glossy white paint will absorb only 14 percent of the solar heat. That tells me that of the the 97 watts per square foot from solar radiation this top will will absorb 13.58 watts...

Amid months of criticism over failed U.S. oil policy, and after suffering embarrasing setbacks in the Senate (Democrats use of rule to demand continued pre-war intelligence committee review) and in the House (Democrat Cong. Murtha's Iraq war exit proposal), the White House and big U.S. oil were...

Suppose a constant volume of water is being heated up by a constant amount of power. After some time it is noted that the rate of change of temperature is slowing down. (In this scenario, assume all temperatures to be between 10 and 90 degrees Celcius) What would cause this non-linear...

A relatively simple question: Suppose we have a dark non-reflective body at rest in space and hit it with fair amounts of radiation. This would cause the body to heat up because it absorbs most of the radiation. After some time would the body cool down? The first guess is that it would, but why...

Spent reactor fuel continues to produce heat for a very long time and I am curious as to why this heat cannot be used for something, such as district heating. Obviously there are some barriers out there or it would be done. I'm wondering what these barriers are. Any discussion surrounding...

Is there a way to determine the "heating power" of a substance with a known specific heat and mass, onto another object of another known specific heat and mass. Say if I had a tank of water and dropped in a piece of metal for example, let the metal heat up, but not let the system come to...

http://www.venezuelanalysis.com/news.php?newsno=1736

Can someone explain to me how the photon energy can heat up a material. Shouldn't the photon energy cause interactions(photoelectric, compton etc.) How can this energy be "absorbed" to make atoms move faster?

Read this article.. http://www.exn.ca/dailyplanet/story.asp?id=2005041952

Suppose here's a covered bottle full of liquid. I heat the bottle so the liquid changes to gas state. Will the bottle be broken since gas creates a bigger pressure?

Well i am doing my physics investigation about temperature, and need an interesting effect that takes place at a precise temperature. I remember watching this thing ages ago on discovery. It was about mining and they needed large quantities of ice. So instead of making it by the normal process...

"In the circuit in the figure, a 20-ohm resistor sits inside 102 g of pure water that is surrounded by insulating Styrofoam." "If the water is initially at temperature 10.1 deg. celsius, how long will it take for its temperature to rise to 58.9 deg. celsius? Use as the heat capacity of...

Can someone help me explain how a plate of metal's yield strength changes as it is 1) Rolled (flattened) then 2) Heated for some hours and cooled, and then finally 3) Cooled and rolled additionally. Does the yield strength increase at first, then drop, and then increase again? That's what I...

I'm currently sitting in a very cold room, it's cold because heating costs too much darn money (we haven't got central heating:(). Well, this got me thinking over cheap ways to heat a room. The idea of heating air with microwaves struck me being really cheap and effiecient. But it's so obvious...

This is what I've got: Iron mass: 81.9g Initial iron temp.: 92'C Water volume: 100mL Initial water temp.: 25'C Final water temp.: 29'C What the the experimental heat capacity of iron? Thanks :) Bjorn

What the heck is isometric heating?

can someone please tell me which equation i need to use for this problem? A 50g metal spoon is placed in a cup with 200g of hot coffee. If the spoon's initial temperature is 20\circ C and the coffee's temperature is 100\circ C , what is the temperature of the spoon and coffee when their...

I am working on a project involving electrically heating clayey soils (having 55% moisture content and 0.5 M salt (nacl/KCl) solutions in the pore space. Does anybody know if electrolysis of water/electrolyte is a concern with AC currents (230 V, 60 Hz frequencies)? Thanks, WWW :smile:

I have this post lab question that I am not sure how to answer... What error in calculation would result if, in the procedure for forming the magnesium oxide, the fumes in the intial heating were allowed to escape? Any help would be great! Thanks!

I need to melt a small quantity (probably less than a cubic centimeter) of a substance at around 200°C in the most uniform way possible and I'd like to have your ideas about how to heat it. Using easily accessible stuff would be better. I've thought of controlling a soldering iron with a...

Hello all, I do not know how to solve this proble and was wondering if you could offer some guidance. Question: How long after it is turned on will a 100-W electric heater take to bring a quart of water to a boil from room temperature 20 deg C? Here's what I know: T_i=20 T_f=100...

The fact that the solar corona has a temperature of a few million degrees has puzzled solar physicists for a long time, considering the comparatively low temperature of about 6000oK at the sun's apparent surface (the photosphere). Clearly, the laws of thermodynamics seem to rule out that a cool...

Heating of the Earth's core must have a logical solution, which led me to this idea, the work done by gravity on vibrating molecules throughout the Earth moves the surface heat of the earth towards the Earth's core,amplifing it as it moves to the Earth's center.This is backed up by the...

Would a heating element have a very high resistance, or a very low resistance? (All comments in this post are based around the fact that the voltage is the same for each situation) I would have thought that a higher resistance would have resulted in more heat loss, but I've been taught that the...

It seems to me that infrared is always considerd responsible for radiant heating. Why is this so, what makes infrared so special when it comes to heating things? I would have thought that higher frequncies would tend to 'feel' hotter, but this doesn't seem to be true.