# What would happen if an object of 689 degrees was in a room

I was just thinking,

If suddenly an object goes about 689 degrees farenheit (365 degrees celsius) in a room, about which perimeter would human life be impossible ?

## Answers and Replies

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In case you need more elements, we will assume that the room is at 59 degrees farenheit (15 degrees celsius).

And let's say the object is a cube of about 5,41 foot tall (1m65).

davenn
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I'm sure the old cast iron pot belly stove/heater in my school classroom many, many yrs ago, got that hot and hotter
it used to roar something dreadful and glow bright red to orange .... used to scare the hell out of me
as a kid or around 10 yrs old

similar to this just a bit taller and fatter

My soldering iron gets to 450C and doesn't even glow red

Dave

PietKuip
I'm sure the old cast iron pot belly stove/heater in my school classroom many, many yrs ago, got that hot and hotter
it used to roar something dreadful and glow bright red to orange .... used to scare the hell out of me
as a kid or around 10 yrs old

similar to this just a bit taller and fatter
View attachment 89772

My soldering iron gets to 450C and doesn't even glow red

Dave
Yes but what about a bigger object ?

davenn
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Yes but what about a bigger object ?
the pot belly was within close range to your measurements
us kids were sitting within 2-3 metres of it

And what about something like 2620 degrees Celsius ?

phinds
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And what about something like 2620 degrees Celsius ?
What is your point with all this? What is it you are really trying to find out. Is there a point at which a large enough, hot enough object would make human life in a room impossible? Sure, but so what?

What is your point with all this? What is it you are really trying to find out. Is there a point at which a large enough, hot enough object would make human life in a room impossible? Sure, but so what?
Well it's pretty much a question after some sentence heard, which was something like "I produce 934% more heat when with you", so I just wandered what would actually happen if such an object just get that hot suddenly in a room, and about what distance would it take to be protected, out of complete curiosity. This is why the question was asked in the "General Discussion" forum.

And what about something like 2620 degrees Celsius ?
That's a bit too high for anyone to sit close to.

The thing is I started thinking the normal body temperature is 37 degrees Celsius. So if you take 934 percent more it goes up to 365 degrees Celsius, which explains my first question.
Then it occurred to me that in a physic way it would be more legitimate in Kelvin. So if we start at 310,15 K (37 degrees Celsius), and add 934% we get to approximatively 2890 (2620 degrees Celsius), which is why I asked the second question.

That's a bit too high for anyone to sit close to.
Yes I know, the real question is how can we find out the good distance not to be harmed ?

I'm sure the old cast iron pot belly stove/heater in my school classroom many, many yrs ago, got that hot and hotter
it used to roar something dreadful and glow bright red to orange ....
According to this:

https://en.wikipedia.org/wiki/Red_heat

steel glowing orange is between 1708 and 1908 degrees F.

I had one of those huge cast iron fireplaces too, our cat would sleep directly underneath it.

A cast iron pan easily gets 400 degrees and not only can you put your hand almost directly above it with no danger, you can actually grab the handle, which is also cast iron and attached to the pan.

It would have to do with how small the room is and how well insulated it was.

russ_watters
Mentor
The thing is I started thinking the normal body temperature is 37 degrees Celsius. So if you take 934 percent more it goes up to 365 degrees Celsius, which explains my first question.
Then it occurred to me that in a physic way it would be more legitimate in Kelvin. So if we start at 310,15 K (37 degrees Celsius), and add 934% we get to approximatively 2890 (2620 degrees Celsius), which is why I asked the second question.
No, radiative heat transfer scales to the fourth power, so the temperature to output 4x more heat is much, much lower than that....though it is complicated for relatively cool objects since they are convection, not radiation dominated.

[Moved to general physics]

cjl
Science Advisor
The thing is I started thinking the normal body temperature is 37 degrees Celsius. So if you take 934 percent more it goes up to 365 degrees Celsius, which explains my first question.
Then it occurred to me that in a physic way it would be more legitimate in Kelvin. So if we start at 310,15 K (37 degrees Celsius), and add 934% we get to approximatively 2890 (2620 degrees Celsius), which is why I asked the second question.
You do have to do it in Kelvin, since that's the only way it makes sense. However, as russ said, radiative heat transfer scales as T4, so to output 9.34 times as much heat, the object would need to be much less than 9.34 times as warm. A human outputs something like 100 watts of heat, so something outputting 934% the heat would be outputting in the neighborhood of a kilowatt. This isn't going to make a room unlivable, nor would it be difficult to stand near - it would be about the same output as a smallish space heater.

davenn and russ_watters
CWatters
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Perhaps look up "power emitted by a black body"

Well it's pretty much a question after some sentence heard, which was something like "I produce 934% more heat when with you", so I just wandered what would actually happen if such an object just get that hot suddenly in a room, and about what distance would it take to be protected, out of complete curiosity. This is why the question was asked in the "General Discussion" forum.
If the "object" is a human being the first thing to happen is that he/she will die and stop producing any heat pretty soon.

sciencemonk
Depends on the time spent, note that a longer duration inside an isolated room with an object of that temperature would cause dehydration. Also if the object is warm enough it can cause damage to the skin. Because two objects tend to mix their temperature, laws of thermodynamics. For example let's say room temp is 15 and the object is 900 whatever unit for both. So for some time the room temp. would have gotten to be 885 units I think. Basically you get the idea, time would be a decisive factor.

To get an answer it just needs to be more specific: Say the room is 4x4x3meters (3 tall) and the object has a one meter square surface facing you and it's in the middle of the room so you are 2 meters away (at best!). We want to know how hot this surface need to be to incinerate you. I'll assume lighting your clothes on fire within 1 second is a sufficient condition. So I'll say your clothing temperature needs to go to 500F or 260C (Fahrenheit 451?). Let's also assume the object has perfect emissivity (e=1, perfect blackbody) and that the your clothing has e=0.50 - half the radiation is absorbed. Further let's say you block 1 m^2 of this radiation. Finally we need the specific heat capacity of the clothing (how fast will it heat up). Let's say about 500 J/C for 1 kilogram of clothing. Starting at room temp we need 130kJ (about a shot glass of gasoline!). Energy from the "object is E = 5.67x10^-8*T^4*A where A we said is 1 and the constant is Boltzmann's in SI. Now if this were a point source we could use 1/r^2 but in this case we need to estimate the fraction area intercepted by our presence. We can assume that total area is the walls of our half of the room (not quite true but good enough) . So the "E" spreads over half the room walls = 2x4x4+4x3 =44m2 (1/2 the area of a sphere 2 meters diameter =50m2). So our 1 meter squared self will absorb 1/44th of E. We want 1/44th of E to equal 130kJ OR 130,000/(5.67x10^-8) = T^4. I get 1230K = 930 C or 1700 F.