physics heat question!?

S

Sarah

New member
why does heat rise up instead of to the side. if we had a candle we can put our hands around the flame b/c theres no heat there, but not above b/c of the air moved up by air convection.


why doesnt it move to the side? is air convection only in one direction?
hah i just realized that i was having a moment.. heat always rises. : /
can you have convection in space? why?
 
The hotter air is the less dense it is.
When there is a density difference between two fluids, the less dense object tries to follow the quickest path to where it will "fit" better. The quickest path just happens to be directly upwards in most situations. You could design a system in which heat from a candle could go to the side though, thisi s not an easy task though.
 
in space, you would be right, heat will expand in all direction thats why it's more dangerous in space, but on earth, the faster moving gas molecules are less dense becus of the space in between each of the gas molecules are greater, making it less dense, and as you know things that are less dense then its' suroundings are less attracted to gravity then its' suroundings so it makes it seem like it's traveling in the opposite direction
 
Air convection is upward because that's opposite to the direction of gravity. It's the same phenomenon as buoyancy. Gravity is responsible for less dense materials having buoyancy when immersed in a more dense medium. Since hot air is less dense than cold air, gravity causes it to rise.
Experiments on the space shuttle and the space station showed that in zero g, there is no convection, and a candle will actually smother in its own combustion products (CO2 being one of them).
 
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