fans are often used to cool us off when the weather is hot and humid. but the air blown at us by the fan is at the same temp as the air in the room. why does the same temp air have a cooling effect
2006-08-01 01:30:49 · 7 answers · asked by cyril_2588 2 in Science & Mathematics ➔ Chemistry
this is an application of bernouli's theorem. in short, it states that a fluid (air is a fluid, by definition) moving at higher speeds has a lower pressure, and vice versa. when the air moves over your skin at higher speeds than the air around it, it has a lower pressure. pressure and temperature are related (gas laws, from chemistry). gasses at lower pressure have a lower temperature. so the air moving across you is actually cooler because it exerts less pressure on your skin than the still air.
2006-08-01 01:37:10 · answer #1 · answered by Anonymous · 0⤊ 0⤋
On a hot n humid day, v sweat.The air blown by the fan speeds up the evaporation of our sweat.Evaporation leads 2 cooling of our body as the sweat absorbs our body's heat 2 evaporate.
2006-08-01 09:16:59 · answer #2 · answered by whatever 2 · 0⤊ 0⤋
Heat is transferred by three mechanisms.
1. Radiation
2. Convection
3. Conduction
A fan uses Convection to remove heat from the body. Your body temperature is 37 degrees Celsius while the room temperature is around 20-25 degrees Celsius. Your body will start to heat up the air around your body. So the fan will move the heated air around your body away, effectively removing the heat. Your body will start to heat up the next batch of air and the cycle goes on and on, cooling your body.
If it is a very hot day and you perspire, the layer of sweat when it evaporates will remove even more heat from your body because of the latent heat of vaporization. The rate of vaporization is again assisted by the fan blowing at you.
2006-08-01 08:57:07 · answer #3 · answered by ideaquest 7 · 0⤊ 0⤋
In hot and humid conditions, a fan will simply displace the hot air elsewhere. Try putting a block of ice in front of the fan and see what happens.
But first, and I feel inclined to explain this, put the block of ice in a tub that will allow drainage or the collection of water, yet be exposed to the fanning.
2006-08-01 08:38:38 · answer #4 · answered by Guitarpicker 7 · 0⤊ 0⤋
Air is isolating, keeping the heat around you, a fan blows it away all the time.
2006-08-01 08:37:12 · answer #5 · answered by Chri R 4 · 0⤊ 0⤋
blowing air evaporates quicker, cooling your temparature
2006-08-01 08:34:26 · answer #6 · answered by kaloptic 5 · 0⤊ 0⤋
monkey blow it
2006-08-01 08:35:39 · answer #7 · answered by Bunnies 1 · 0⤊ 0⤋