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Why does a heated body emit a continuous spectrum of waves, while a burning body emits one color?

Why does a heated body emit a continuous spectrum of waves (as I understand it, that's why they burn red/white/blue), and a burning body is one color? as I understood it, for example, the green flame ...
buujek's user avatar
  • 13
7 votes
3 answers
2k views

Will a piece of coal burn at the atomic level at room temperature?

If there is a piece of coal in the open air at room temperature, some of the molecules in the surrounding air will have sufficient velocity to oxidize the carbon in the coal. Will the surface of the ...
Belu boy's user avatar
0 votes
4 answers
78 views

Can we use Internal Combustion Engine exhaust to give heat for electrolysis to get hydrogen from water, to be used as fuel in the ICE?

Can we use exhaust from an Internal Combustion Engine to provide heat for the process of the electrolysis (to get hydrogen from water). And then use the H2 as fuel for the ICE so we use very little ...
Kenny Chu's user avatar
1 vote
4 answers
146 views

General Doubt. My doubt about combustion

When we give flame to a newspaper it burns readily. What we need for a fire (fuel, heat, Oxygen) is also known as the fire triangle. But why does the paper not burn when we pour boiling water over it? ...
Gautam's user avatar
  • 47
0 votes
1 answer
48 views

How does the height of the hole on the bottle affect the burning time of the candles?

We took 3 identical bottles and drilled some holes on the side, each bottle had a hole but at different heights. Then we covered the burning candles with the 3 bottles and measured the burning time. ...
qsfhubv's user avatar
0 votes
0 answers
32 views

If I burn a log & contain all the matter, will the burned log weigh $E/c^2$ less than the unburned log, with $E$ being the energy from light & heat? [duplicate]

I understand that the change in weight would be tiny even to a physicist and nothing for any practical purpose. I am also not talking about smoke and water vapor. I am only referring to energy given ...
John Bonner's user avatar
1 vote
0 answers
50 views

Would a candle in very high gravity blow itself out?

A candle creates an upward draft of hot air, without which the flame would be spherical. The buoyancy generated is proportional to the density difference as well as the strength of gravity. Suppose a ...
Kevin Kostlan's user avatar
-1 votes
2 answers
71 views

Does fire cause friction in the fuel?

It is possible to create fire by friction. For example - by striking a stone with another stone or by striking a matchstick on a rough surface. My question is: Can we say that, where there is fire ...
Dheeraj Verma's user avatar
0 votes
2 answers
90 views

Why does force decrease with increase in velocity in case power was constant?

Suppose an internal combustion engine burns the same amount of fuel every cycle (regardless of engine or car speed ) that means it creates the same pressure every cycle and the force on the piston due ...
John greg's user avatar
  • 103
1 vote
1 answer
52 views

Would there be a flame front in an air-fuel mixture? [closed]

Suppose a piston enclosing an amount of air-fuel mixture and then this piston compresses the mixture to the point of auto ignition, if every part of the mixture ignite simultaneously is it safe to say ...
John greg's user avatar
  • 103
0 votes
3 answers
164 views

What's the $T$ around a candle?

I think most of you have already heard of the candle lift/elevator. It's a funny experiment that is easy to perform too. If you don't know what I'm talking about I would recommend you to watch the ...
dark_ursus's user avatar
12 votes
3 answers
3k views

Can we call rusting of iron a combustion reaction?

In case of rusting of iron the chemical reaction is not fast enough. The oxygen used is not molecular oxygen from the atmosphere but it is the oxygen from water molecule. The reaction is not rapid and ...
Shinnaaan's user avatar
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0 votes
3 answers
1k views

I don't understand why combustion releases energy?

So I've tried to wrap my head around fire. To keep it simple, I explain it with cellulose combustion. But to explain exothermic reactions, I show the example of methane combustion. Here is the detail ...
Rom's user avatar
  • 217
0 votes
1 answer
91 views

If there is no oxygen in space what does the sunshine burn for fuel? [duplicate]

Since there is no oxygen in space how does the sun burn fuel?
Amy lesueur - Paquena's user avatar
0 votes
1 answer
148 views

How does an internal combustion engine reduce the heat produced by burning fuel?

If I understand correctly, any heat produced by an internal combustion engine can be considered "waste heat"; energy from the fuel that did not get converted to mechanical energy. But if you ...
Lorry Laurence mcLarry's user avatar
0 votes
1 answer
690 views

Why do engines compress the air-fuel mixture prior to combustion?

In a basic Otto-cycle internal combustion engine, the air-fuel mixture that is drawn into the cylinder is compressed prior to the spark plug initiating the combustion process. Why is is beneficial to ...
interested22's user avatar
3 votes
3 answers
1k views

How does an exothermic reaction release energy? [closed]

When a reaction is exothermic it releases energy often denoted in kJ/mol. This is due to the total enthalpy of the reactant(s) being higher than the enthalpy of the product(s) and thus needs to ...
Noah's user avatar
  • 139
-2 votes
2 answers
113 views

May the chemical energy of combustion be wholly released as photon only?

It may be the burning of wood, LPG gas, hydrogen, gasoline. The energy is released wholly as photon and it is the absorption of photon by matter that heats up everything else increasing their kinetic ...
itsme's user avatar
  • 159
0 votes
0 answers
79 views

If the human eye can see green so well, why don't flames and such that emit a broad rangecof wavelengths ever appear green?

Similar questions have been posted many, many times before, but.... If a black body at the correct (average) temperature is 'centered' on the green, and human eyes our retinal cones) see best in the ...
Kurt Hikes's user avatar
  • 4,515
3 votes
5 answers
261 views

Is there an 'intuitive' explanation for "Which burns more?"

In helping a friend's son with his grade 10 science homework, I came across a question that essentially asked the following: "If two objects of equal mass but different specific heat capacities ...
A.J.'s user avatar
  • 161
0 votes
1 answer
72 views

A combustion engine uses cylinders to compress air and fuel before igniting it

The piston moves up to compress the mixture before exploding and sending the piston down with great force. Would there be any improvement if the piston were turned upside-down? This would mean the ...
MATIAS SOLANO's user avatar
0 votes
1 answer
571 views

Why does air not flow backwards in Jet Engines in the combustion chamber? [duplicate]

In jet engines air is taken in, compressed and then fuel is injected and then ignited forcing the turbine to spin powering the compressor. What I am curious about is why the combusted air isn't forced ...
FourierFlux's user avatar
1 vote
1 answer
681 views

Why do internal combustion engines use adiabatic expansion and combustion?

In the gasoline engine, the gasoline mixture is heated at constant volume, followed by adiabatic expansion. In the diesel engine, the mixture is heated at constant pressure, and this is followed by ...
Piksiki's user avatar
  • 65
-1 votes
2 answers
70 views

Can I use combustion gases for heating?

What is the temperature of the carbon dioxide gas released from combustion of wood? If I let the gases escape directly, then only some heat is transferred by the gas to the heating drum and the rest ...
Amit Agarwal's user avatar
1 vote
1 answer
26 views

Adding extra gas to a high velocity burner but the temperature in the vessel won't rise

So I'm doing a refractory dryout of a vessel and I'm stuck at 350°C. Normally I would add some more gas to the burner and the temperature would go up, but now it just stays at the same level. I've ...
vennot_be's user avatar
0 votes
1 answer
56 views

Why is all heat released by a deflagration wave conducted upstream?

I'm having some trouble understanding the phenomenological analysis used to calculate the thickness of a 1D deflagration wave (Combustion Theory by Williams, page 135). I quote the text below: ...
Tofi's user avatar
  • 2,659
1 vote
2 answers
87 views

Can carbohydrates in powdered form provide a more 'energy efficient' alternative solution to traditional combustion engines?

In my high school chemistry class I am studying the affect of surface area over the rate of reaction. In this case, using Collision Theory to describe how a high surface area to volume ratio ...
Hector Yang's user avatar
0 votes
1 answer
147 views

How sound waves are generated in IC engine?

I have found the source of sound in the IC engine as aerodynamic, combustion, and mechanical. But I want to know which among the 3 is the major source. Also what happens during the combustion of fuel ...
Sonali Pansare's user avatar
0 votes
1 answer
145 views

Why does a gunpowder makes sound when it burns but not like a candle?

My class teacher asked this question, when a fire-cracker ( which has gunpowder in it) burns, it explodes and make a sound while when a candle is burnt it doesn't, and I also want to know why does ...
Idk's user avatar
  • 101
0 votes
2 answers
375 views

Why light comes from fire?

We know that light is produced when a charge particle accelerates. Fire doesn't have electric and magnetic field so how does light come from a fire?
user avatar
1 vote
1 answer
49 views

Can ionizing particles cause ignition of flammable material?

For example, can high energy $\alpha$ or $\beta$ particle cause ignition of $H_2/O_2$ mixture below critical conditions?
Batou's user avatar
  • 13
-1 votes
3 answers
577 views

Why is the burning temperature of different species of wood so different? [closed]

If you have read Farenheit 451, you may have the idea that paper (or perhaps wood in general) burns at 451F. However, in fact, different species of wood burn at widely different temperatures. Here is ...
Ambrose Swasey's user avatar
0 votes
2 answers
759 views

How much oxygen does it take to burn a log of wood?

How much oxygen does it take to burn a log of wood? This is kind of a complex question because the wood itself contains oxygen, so it is not as simple to just compute how much carbon is in the wood ...
Ambrose Swasey's user avatar
2 votes
0 answers
43 views

What happens to the composition of a mixed gas plasma when de-ionizes back into a gas

I've been thinking about this question for the past few days, but I'm not very well versed in plasma physics. I am an aerospace engineering student in my senior year of college. A little while ago, I ...
Mattias's user avatar
  • 149
2 votes
2 answers
314 views

Is combustion a phase transition?

Is combustion a phase transition? Premise If we take a chemical reaction $$ A + B \leftrightarrow AB, $$ we expect all the three chemicals, $A,B, AB$ to be present in the mixture, in the proportions ...
Roger V.'s user avatar
  • 60k
1 vote
2 answers
58 views

How actually Gave and wax candle works? [duplicate]

I have seen a candle and gave (diya) burning. But how exactly they work. Because in candle we use wax but we also use a thread like structure to burn it, although if we try to burn simple wax by ...
Suresh Chandra Pal's user avatar
0 votes
0 answers
58 views

Why is the the temperature change due to the combustion of paraffin wax so high (10000 Kelvin)?

I'm trying to work out the temperature change (I got something like 10k Kelvin,hotter than the Sun's core...) caused by the combustion of paraffin wax which has a molar enthalpy of combustion $E^{wax}...
Chern-Simons's user avatar
  • 1,047
3 votes
1 answer
206 views

Does burning something with higher temperature make the burning faster?

Like if I burn wood at 500 C, or 1000 C, is there a relationship? Any equation that model this? Thanks
GonzaloUrroz's user avatar
12 votes
5 answers
6k views

Fire caused by friction with water

Friction causes heat and heat causes fire, but could something catch on fire because of friction with a high speed water stream? If so, what material would it be and how fast would the water need to ...
Samuel Fyckes's user avatar
0 votes
1 answer
393 views

Minimum temperature of a smouldering fire? Read below

What is the lowest temperature in the hottest part of the ember of an oxygen starved low temperature smouldering fire the hypothetical fire glows a dull and faint orange at night, not red but orange, ...
Thomas Barnable's user avatar
6 votes
3 answers
3k views

How are "cold sparks" possible?

At raves, nightclubs, and parties, sometimes there are "cold fireworks" machines that spew out a dense bunch of really bright sparks. The odd thing is that these machines are apparently safe ...
KF Gauss's user avatar
  • 7,931
6 votes
3 answers
1k views

Color of a flame [duplicate]

I use an LPG (liquefied petroleum gas) gas stove at home for cooking purposes. I notice that, in the flame, the bottom part is almost always blue but the top has a yellowish-orange color. Why is that? ...
PhysicsWizardUd's user avatar
0 votes
1 answer
149 views

How will the compression ratio increase thermal effeciency of otto cycle while Win is higher?

Why the ideal otto cycle thermal effeciency increase with compression ratio although that will increase work input? While the temperature difference in the combustion chamber could be low,the overall ...
Carlos Werbock's user avatar
19 votes
5 answers
6k views

Does fire emit black-body radiation?

Question: Can the radiation emitted by fire be approximated by black body spectrum? It has been discussed in this community that black-body spectrum mostly serves as an approximation to actual spectra ...
Roger V.'s user avatar
  • 60k
31 votes
8 answers
11k views

If air is a bad conductor, how does fire heat up a room?

If air is a bad heat conductor, how does fire heat up a room? Could someone help me, as I really don't get this?
Kaira Chunawala's user avatar
0 votes
1 answer
52 views

Absolute entropy of methane at 111 K

I have to analyse a combustion process. One of the inputs of the process is methane at 1 bar and 111 K. To apply the second law of themodynamics I have to calculate $\overline{s}(111 K, 1 bar)$. By ...
Eduardo's user avatar
  • 175
2 votes
1 answer
47 views

Why does hot oil inflame when windows are opened?

A Japanese Youtuber posted a video on her survival from burns on one side of her face. She said left oil heating on the stove and noticed it producing lots of black smoke- hit the smoke temperature ...
user2617804's user avatar
7 votes
7 answers
5k views

Can I burn a piece of wood by emitting only one photon per second on it?

Can I burn a piece of wood by emitting single photons on it? (for example by emitting only one photon per second or per milisecond etc to the wood). How much should be the rate of emitting single ...
mathLover's user avatar
  • 366
0 votes
1 answer
684 views

Why combustion need oxygen?

Why actually oxygen is needed for combustion?, can combustion take place with other element? Or oxygen is the only gas involving in this chemical reaction?
SURAJ SINGH's user avatar
6 votes
2 answers
2k views

The process of burning and increasing weight

I saw a movie in which an object (a kind of steel wool in kitchens) was burning on the kitchen scale. When the burning process began, the weight of the object began to increase. Can anyone explain the ...
SG8's user avatar
  • 4,580