Why does a candle flame defy gravity?
(Retnawati, Singapore) A: A flame goes up because the denser surrounding air pushes it up. Fire bobs up through surrounding denser air much as a cork rises to the water surface pushed by greater pressure from denser air below. [Photo Credit:US Fish and Wildlife Service] A flame consists of gases so hot they glow yellow, orange, and red. Hot gasses expand and become less dense than the surrounding air. Therefore, the flame is lighter than an equal volume of air. A flame goes up much as a submerged cork bobs to the water surface when released. The flame is lighter than air and the airs buoyant force is, therefore, strong enough to push the flame up. Actually, the flame doesnt defy gravity but rather the flame goes up because of gravity. Gravity causes buoyancy. Buoyant force. In the third century BC, Archimedes discovered the buoyant force when he settled into a bath of water, legend has it, and felt lighter as his body displaced the bath water. Weve encountered the same lightness as we
