Can someone explain this sentence to me. What is convection?
2006-07-12 06:48:38 · 11 answers · asked by MyStErY wHiTe BoY 2 in Science & Mathematics ➔ Physics
If you heat up water its molecules get heated up become lighter compared to unheated molecules around and therefore rise.This movement causes convective currents. Same thing is true of convective currents in air too. So much for convection.
For a flame to exist two things are necessary. A fuel and an oxidant. Consider a candle. Wax or the organic compound there in is the fuel. Oxygen in the surrounding air is the oxidant.
Assuming there is fuel and oxidant in zero gravity condition, say in space, you will have flame which would be spherical. A normal flame as we see it on earth stands up due to presence of air around and due to convective air currents moving upwards.
2006-07-12 07:12:03 · answer #1 · answered by openpsychy 6 · 0⤊ 1⤋
Convection is fluid motion, in the this case air. Free convection is convection caused by inherent instabilities in the fluid. On earth, or anywhere with gravity, the heat released from the chemical burn causes the products of the combustion, CO2 and H2O, to rise upwards. To fill the resulting low pressure fresh cooler air is pulled in to take the hot airs place. This brings in fresh oxygen to continue the burn, and clears out the waste from the combustion. In zero gravity there's no reason for the hot air to rise, everything is weightless, so CO2 and H2O build up locally around the flame, and no oxygen will come in to replace it, thus extinguishing the flame. Rockets burn because the oxidizer is mixed into or part of the burning compound and therefore cannot be starved. This question applies to solids burning in a oxygen environment, for example a candle would not burn on the space shuttle for very long.
2006-07-12 14:05:53 · answer #2 · answered by santacruzrc 2 · 0⤊ 0⤋
Convection is the transfer of energy by a fluid. On earth (or wherever there is gravity) a fire is fueled by buoyancy driven convection (i.e. heat rises). This is impossible without gravity. A fire can still burn in zero gravity, but it will be controlled by molecular diffusion. This process is much slower and the burning process is much reduced, compared to a gravity based flame.
2006-07-12 14:00:34 · answer #3 · answered by bromothymol 4 · 0⤊ 0⤋
Convection is the movement of hot air upwards due to it being lighter than the cool air, this movement includes the drawing in of the cool air to supply the burn. This however is a very limited statement. Yes the wood burning stove would not draw air so it would starve. open air fires will indeed burn as the simple expansion of the air will cause additional stirring.
2006-07-12 13:55:55 · answer #4 · answered by Anonymous · 0⤊ 0⤋
Convection cannot happen because there can be no relationship, in zero gravity, between the molecules in fluid in order to turn it into heat.
2006-07-12 13:54:24 · answer #5 · answered by carolinagrl 4 · 0⤊ 0⤋
Convection is one of the properties of heat transfer. fire does burn in zero gravity, and it looks really cool.
2006-07-13 11:34:58 · answer #6 · answered by Hawlass 2 · 0⤊ 0⤋
Convection is the transfer of potential energy, for example heat, by currents within a fluid.
2006-07-12 13:53:19 · answer #7 · answered by Answer King 5 · 0⤊ 0⤋
No such thing as zero gravity. There is less gravity but no such thing as zero gravity. Nothing in the convection equation about gravity so my guess is that is wrong.
2006-07-12 14:07:57 · answer #8 · answered by DoctaB01 2 · 0⤊ 0⤋
Fire will still burn in zero gravity in the space. Example: Rockets are nothing but fire.
Convestion : Read others comments
2006-07-12 14:02:03 · answer #9 · answered by Dr M 5 · 0⤊ 0⤋
I think we all assumed that the question was talking of zero gravity in outer space.
Zero gravity can be mimicked in a free falling plane. Thus the O2 is present to allow combustion of material.
2006-07-12 17:44:53 · answer #10 · answered by johnnyquest 3 · 0⤊ 0⤋