Fire and Gravity

[Bhaal-Zebub]

The other day, I was talking to my father about how the earth was made, and how larger objects attract smaller objects and so on. But the discussion took a bit of a turn into, wheather or not fire obeys the laws of gravity. Unfortunatly we could not come to a conclusion, mostly because of our limited knowledge in this matter. So I put the question to you, does a flame obey the laws of gravity if hypothetically the weight of it's source (eg: a lighter, a fag ect) and oxygen was not a factor in weighing it down?

[Thanatos]

NASA is understandably paranoid about fire in space, but they did light a match in space once and take pictures. It looks really odd without convection to give it the normal flame shape.

A Flame in Microgravity, aka 'Zero Gravity' (Event Horizon) - YouTube

Flames are made of hot gases. Those gases have mass, but they're also so hot and low-density that they float in air - this makes flames rise bouyantly. Microgravity means there's nowhere for them to rise to, so flames look funny.

You also can't start a fire outside the ISS for testing (sorry pyromaniacs) because fires require oxygen or another highly reactive gas, and space is a vacuum. In the event of a serious fire inside a spacecraft all you'd have to do to put it out would be to open a window and then watch all the flames, smoke and remaining oxygen disappear. I think the Russians had to do that once.

[Angry Citizen]

Flames are made of hot gases.

Technically they're made of hot plasma. But essentially you're correct. The plasma is massive, and it is affected by gravity.

[xx_mortekai_xx]

Technically they're made of hot plasma. But essentially you're correct. The plasma is massive, and it is affected by gravity.

and the hot plasma is affected by gravity less than the relatively cool air around it (since the hot plasma is less dense than he relatively cool air), and therefore rises.

[xx_mortekai_xx]

NASA is understandably paranoid about fire in space, but they did light a match in space once and take pictures. It looks really odd without convection to give it the normal flame shape.

A Flame in Microgravity, aka 'Zero Gravity' (Event Horizon) - YouTube

Flames are made of hot gases. Those gases have mass, but they're also so hot and low-density that they float in air - this makes flames rise bouyantly. Microgravity means there's nowhere for them to rise to, so flames look funny.

You also can't start a fire outside the ISS for testing (sorry pyromaniacs) because fires require oxygen or another highly reactive gas, and space is a vacuum. In the event of a serious fire inside a spacecraft all you'd have to do to put it out would be to open a window and then watch all the flames, smoke and remaining oxygen disappear. I think the Russians had to do that once.

didnt they do that for far too long once and kill all three passengers? I think it was Soyuz 11, if i am remembering right.

[seyorni]

Even without evacuating the air a fire in zero gravity would tend to snuff itself. Without gravity there would be no convection feeding the flame or carrying off the spent combustion gasses. It would choke on it's own oxidized 'waste'.

[xx_mortekai_xx]

Even without evacuating the air a fire in zero gravity would tend to snuff itself. Without gravity there would be no convection feeding the flame or carrying off the spent combustion gasses. It would choke on it's own oxidized 'waste'.

very good point. Convection IS kinda essential to a self sustaining flame, i suppose. And convection is necessarily dependent on gravity.

[samson]

The other day, I was talking to my father about how the earth was made, and how larger objects attract smaller objects and so on. But the discussion took a bit of a turn into, wheather or not fire obeys the laws of gravity. Unfortunatly we could not come to a conclusion, mostly because of our limited knowledge in this matter. So I put the question to you, does a flame obey the laws of gravity if hypothetically the weight of it's source (eg: a lighter, a fag ect) and oxygen was not a factor in weighing it down?

If the laws of physics are indeed laws in that it is true in every circumstance that it describes, then every thing described by physics, including what you have described, must follow the laws of physics.

Fire does follow the laws of physics in that relatively hotter gases, or plasma, are relatively less dense than the gases surrounding it. As it has been proven, relatively less dense gases will rise when the environment is relatively more dense.

NASA is understandably paranoid about fire in space, but they did light a match in space once and take pictures. It looks really odd without convection to give it the normal flame shape.

A Flame in Microgravity, aka 'Zero Gravity' (Event Horizon) - YouTube

Flames are made of hot gases. Those gases have mass, but they're also so hot and low-density that they float in air - this makes flames rise bouyantly. Microgravity means there's nowhere for them to rise to, so flames look funny.

You also can't start a fire outside the ISS for testing (sorry pyromaniacs) because fires require oxygen or another highly reactive gas, and space is a vacuum. In the event of a serious fire inside a spacecraft all you'd have to do to put it out would be to open a window and then watch all the flames, smoke and remaining oxygen disappear. I think the Russians had to do that once.

Fires does not necessarily need oxygen.

and the hot plasma is affected by gravity less than the relatively cool air around it (since the hot plasma is less dense than he relatively cool air), and therefore rises.

Gravity affects atomic particles all the same. Using Earth as an example, regardless of whatever atomic particle you have, all the particles will experience an acceleration of 9.8 m/s^2 due to gravity.

Even without evacuating the air a fire in zero gravity would tend to snuff itself. Without gravity there would be no convection feeding the flame or carrying off the spent combustion gasses. It would choke on it's own oxidized 'waste'.

Convection is not necessarily needed for a fire, specifically combustion. You can look at the design of the rockets and engine of the Space Shuttle as an example.

[xx_mortekai_xx]

Gravity affects atomic particles all the same. Using Earth as an example, regardless of whatever atomic particle you have, all the particles will experience an acceleration of 9.8 m/s^2 due to gravity.

My mistake, you are correct. The hot plasma is more buoyant in the surrounding cool air, and floats, causing convection to occur.

[Thanatos]

Fires does not necessarily need oxygen.

While I am always open to new ways of making things burn, I was under the impression that you needed a strong oxidizer of some sort to have a proper fire.

[seyorni]

OK, to clarify then: In ordinary combustion, using exogenous oxygen, convection is important.
Light a match on the International Space Station and it should flare up for a moment and then snuff itself, leaving a little ball of smoke hanging in the air.

[minorwork]

OK, to clarify then: In ordinary combustion, using exogenous oxygen, convection is important.
Light a match on the International Space Station and it should flare up for a moment and then snuff itself, leaving a little ball of smoke hanging in the air.

What is going on with the not ordinary fire that oxygen is not required? You talking catalytic stuff as in some non typical type of fire? Passing hydrogen peroxide over a catalyst? You'd call that a fire?