2007-02-13 14:59:26 · 3 answers · asked by adrian2chavez@sbcglobal.net 1 in Science & Mathematics ➔ Physics
Gravity
Fire points up because hot air rises. This act of the air above the fire moving up causes more fresh air to move in from the sides. The air moves like a cone from the bottom toward the cone's apex.
Gravity is the cause because without gravity the notion of 'up' has no absolute meaning in reference to the flame.
In space, flames are more like sparklers and bubbles for this reason. Flame doesn't burn very well in space because there is no air current caused by 'rising' air to bring oxygen to the flame. Rather, the expansion of the air due to heat pushes away from source in all directions. This prevents fresh oxygen from getting to the flame so it doesn't burn as well.... it finds an equilibrium where the balance between required oxygen and flame intensity is much lower than when gravity can provide an effect on the motion of less dense vs. more dense air.
2007-02-13 15:29:18 · answer #1 · answered by Justin 5 · 0⤊ 0⤋
Fire bobs up through surrounding denser air much as a cork rises to the water surface — pushed by greater pressure from denser air below.
2007-02-13 23:17:04 · answer #2 · answered by Anonymous · 0⤊ 0⤋
I say, fire is a gas and it is lighter than air
my husband says: Heat rises
2007-02-13 23:11:16 · answer #3 · answered by thezookeeper 4 · 0⤊ 1⤋