why do flames of a candle upwards? dont it have any relation with gravitational force.?
143411
This IS related to gravity.  Hot air rises because it is less dense (and therefore weighs less).  This is not true in zero gravity.  If you search NASA's website, you will find pictures of candles burning in 0g.  They are perfectly round.
277723
Specific gravity is the ratio of the density of a material to the density of water. The density of water is about 1 gram per cubic centimetre (g/cc). Materials which are lighter than water (specific gravity less than 1.0) will float. Most materials have specific gravities exceeding 1.0, which means they are heavier than water and so will sink. Knowing the specific gravity is important for planning spill clean-up and fire fighting procedures. For example, a light flammable liquid such as gasoline may spread and, if ignited, burn on top of a water surface. \n\nThis principle can be very vital in fire extinguishers. For example, you cannot use a water based fire extinguisher to douse a flame arising out of burning oil. The oil, on account of its lower specific gravity will simply float to the surface of the water and continue to burn. On the other hand you could use a foam based fire extinguisher which will float on the oil, cut the oxygen supply to the burning flame and extinguish it eventually. :)
122399
Spontaneous combustion is real although it's causes are not understood.  I wouldn't spend too much time / effort worrying about suddenly bursting into flames though, it is extremely rare.  Aliens might exist although undeniable proof of their existence has eluded us up to this point.  It is likely that somewhere on one of the hundreds of billions of planets in our universe life could be and is supported.  I'm guessing we will never encounter them during our lifetimes, and probably not for thousands of years to come, but if we keep looking who knows what we will find, or what might find us.
11248
Oxygen is what fuels fire, but when we blow out a candle there is so much force in your breath that the flame is blown out otherwise it would only make it bigger. Oxygen is highly flammable, carbon-dioxide is a fire suppressant.
4800
Normally on Earth, smoke rises and spreads because 1) the smoke particles are lighter than air, 2) the heat from whatever is burning creates an upward current of air, and 3) air is always moving.\n\nIf this vacuum is on Earth, than the smoke particles will fall to the bottom of the container or room.  If the vacuum is in space, then it depends on how the smoke is generated.  The smoke particles might either just sit there or fly straight out.
1000475
The sun holds early spiritual significance. Fire, as an element of the sun, was used to light candles in weddings, funerals, and other rituals. Fire was viewed as a symbol of beginning, or birth, as well as essential for sustaining life.\n\nIn a talk given to the Culinary Historians of Washington, DC, Shirley Cherkasky explained that candles were instrumental in measuring time, pointing to King Alfred of England's ninth-century system of measuring the day's hours with candles. Measuring or signifying the years of someone's life using candles isn't such a far jump.\n\nA book called "The Lore of Birthdays" is cited by abcog.org regarding the first cake and candle combo. "The custom of lighted candles on the cakes started with the Greeks," who placed the cakes at the altars of the temple of Artemis. However, it's not clear if these were birthday cakes or cakes for another occasion.\n\nCherkasky's extensive research points to a 1799 letter by Johann Wolfgang von Goethe. According to the letter, a well-lit birthday cake was used by the Germans in or before the 18th century. Employees of a prince "carried a generous-size torte with colorful flaming candles -- amounting to some fifty candles -- that began to melt and threatened to burn down, instead of there being enough room for candles indicating upcoming years, as is the case with children's festivities of this kind."
147880
>>>Can gravity be used as a means of propultion?\n\nIt can and it is. Have you ever seen a flying squirrel? Or a petrel diving on a fish? They are using gravity as a means of propulsion. \n\n>>>>>For instance if it is possible to create a device which "bounces" off of gravity. \n\nYou can’t ‘bounce off’ gravity. Gravity is an attractive force, not a repulsive. \n\nThe suggestion is nonsense. You might just as well ask whether you can stand at the top of a well and use the hole to fall up to the sky. \n\nOr maybe ask whether you can use the negative speed of a stationary vehicle to get back where you came from. \n\nIt makes no sense in a  ‘sunbeams trapped in a jar as a nightlight’ kind of way.\n\n\n>>>>>somebody said "gravity is an attractive force"\n>>>>> therefore it is a force... so what about the concept >>>>> of anti-gravity?\n\nThat's way outside my ability to comment on. Anti-gravity depends on the production of anti-gravitons. We don't even know if gravity is caused by gravitons yet, we've never seen one. We've ceratinly never been able toproduce an anti graviton. It's all science fiction stuff. I gather it's possible in theory if certain theories are correct, but in practice.....
430522
Like charges do not attract eachother.\n\nLike gravity does, but charges do not.
618210
Not due to gravitational pull?!
940903
Well, the flame is a reaction with air at a certain temperature range. At the base, the heat radiates only a short distance. Above the wic, the heat travels upward (hot air raises), so the length of the flame follows this.
392411
The scientific explanation is that it doesn't happen. They're still arguing over it.\n\nhttp://en.wikipedia.org/wiki/Spontaneous_human_combustion
1028116
You asked a very good question. This very question plagued me for many years since childhood. I commend you for asking this question because most people take the experience of fire for granted and never even thinking about what it is.\n\nFire is the result of a chemical process (specifically it is the oxidation of carbon which results in the release of energy, aka heat, and carbon dioxide). So fire is NOT matter, and it is NOT the fourth phase of anything.\n\nSo what exactly are we looking at then when we look at fire? First, you are looking at the photons being released when a carbon atom is combined with 2 oxygen atoms. The carbon comes from the material being burned, which can be a piece of wood, charcoal or paper. The oxygen comes from the air (of course). But aside from visible light, you can also feel heat which is basically light in the infrared wavelength range.\n\nNow if you look closely, you will notice (1) the flame has different color, and (2) it wavers and shapeshifts in the air. The colors are due to the different temperatures that the burning process has achieved. Blue is hottest, then white, yellow, orange and red. The shape of the flame is basically where oxidation and release of energy is taking place. It can waver and change shape because (1) there can be air currents, and (2) the release of heat itself generates air currents that causes the flame to waver or shapeshifts.
1062457
Trust NASA on this one, they know what they are talking about. Matches burned in outer psace produce spherical flames.\n\n\nThe sequence of pictures, at the bottom of this page, illustrates a combustion experiment conducted at the NASA Lewis Research Center 132 Meter Drop Tower. ... Instead of the typical teardrop shape seen on Earth, the microgravity flames becomes spherical.
609073
I don't think that fire would properly have a volume since it is a form of energy. Energy is measured differently than physical mass, usually by intesity of energy present. Fire is measured by it's intensity of heat and combustion.
1156049
It burns  with more of a round shape than a flame on earth. In a gravity environment the hot gases move up and effect the shape of the flame (where the gases are combusting).\n    \nUnless the flame has air moving past it, it will soon go out, because the burnt gases stay around the flame rather than rising up.
668137
According to Archimedes Principle, the upthrust force on a body totally or partially immersed in a fluid is equal to the weight of the fluid displaced by the body. \n\nImagine a ship that has a weight of 2,000,000 N.  A large crane is lowering it into the water.  When a part of the keel is submerged, it displaces, say 500,000 N of water.  There is still a net downwards force of 1,500,000 N.  If lowered further, more water is displaced, and therefore the upward force increases, while the net downward force decreases.  There comes a time when the ship, as it continues to be lowered, has displaced 2,000,000 N of water.  What then?  The upward force just balances the weight of the ship, and it sinks on further into the water.\n\nIncidentally, a needle does not always sink in water.  Smear it with oil and gently lower it in a bowl of water.  It floats!!!  Of course, this has nothing to do with Archimedes Principle but rather with the surface tension of the water molecules.
448071
Because of it's position. If it's vertical. it would fall faster. If it's horizontal, there is more space for the air to push it up. It would fall slower because air molecules pushes it up as the leaf pushes air down. Have you heard of "Action-Reaction". All objects exert force to one another. Hope that helps.