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I would like to have the answers in short abou t the following :
a) Why asteam burn is worse than a hot water burn?
b) A pressure cooker cooks food faster
c) A car cooling system is usually pressurized
d)An astronaut needs a pressurized space suit all round his body
e)It is difficult to make tea on Mount Everest
f)Wet clothes feel cold
g) Tea is cooled more rapidly by blowing on it
h) Atheletes should put on a tracksuit soon after finishing a race
I) A swimming pool is colder on a windy day
Why a steam burn is worse than a hot water burn?
Beshooraa - you do know that steam is hotter than water, right?
I'll try and help.
a. see above
b. pressure increases energy which in turn increases the "heat" used for cooking
c. There are several reasons Google them.
d. There are several reasons. Temperature, oxygen circulations, look up nasa.gov
e. Yes, because usually the tea is frozen and there is no electricity.
f. Because when water evaporates it is an endothermic reaction. It absorbs heat for it to turn from water to water vapor. Water can also "hold" lots of heat.
g. When you blow cold air at anything it tends to "carry" off heat.
h. Don't think this is really needed other than to help save time.
I. Water absorbs large quantities of heat without having massive changes in temperature.
j. Why ask these questions?
For e), it's actually because at a lower pressure the boiling point of water is lower. Because of this it will boil at a lowere temperature and it will be inpossible to make hot water. The water will boil off before it becomes hot enough for a good cup of tea :)
I would figure the electricity part would precede the ability to warm the water up :P
a) Actually steam is NOT hotter than water. Steam and water can both exist at 100 degrees Celsius. A steam burn is worse than a hot water burn because the steam is in a different phase. When the steam comes in contact with your body, the steam must turn into water before it can cool down to body temperature. This releases more energy into the skin due to the phase change, thus causing a worse burn.
d) A non-pressurized suit would still keep in oxygen and could regulate temperature. In space there is no pressure. Your body is specifically designed to deal with atmospheric pressure. Your cells push out with the same pressure as the atmosphere. If you go to space (Where there is no atmosphere) your cells will still push out and start to explode. You would die. You need the pressurized suit to simulate the atmosphere.
g) Convection
Depends whether you mean "hot" as in temperature, or "hot" as in heat energy. I would say that steam is hotter than water (pour some 100C water on your arm and spray some 100C steam on your other arm and tell me steam isn't hotter). Even though they are at the same temperature, steam has more heat energy, which I would term as being hotter.Quote:
Originally Posted by Physics Goddess
You can circulate oxygen in a non-pressurized suit in a vacuum? How? You are right about the steam thing. Physically it releases energy when it converts to back to water.Quote:
Originally Posted by Physics Goddess
Well technically you could have an external tank that supplies the oxygen. I realize that this is not how it is done with actual suits as they serve multiple purposes, but a pressurized tank would allow for oxygen circulation. There are actually a couple of really good sites out there that discuss all the functions of a space suit if anyone is interested. One good one is...Quote:
Originally Posted by enigmagnetic
Howstuffworks "Spacesuit Capabilities"
a) Actually steam IS hotter than water. U are right about the part of Steam and water can both exist at 100 degrees Celsius however it takes a lot of energy for water at 100 degress celsius to change to steam at 100 degrees celsius. The steam release 2 260 000 joules of energy as there is a rapid change of state from steam to water when in contact with the skin.
a) Actually steam IS hotter than water. U are right about the part of Steam and water can both exist at 100 degrees Celsius however it takes a lot of energy for water at 100 degress celsius to change to steam at 100 degrees celsius. The steam release 2 260 000 joules of energy as there is a rapid change of state from steam to water when in contact with the skin.
F) Simply water has a higher heat capacity than air (80% Nitrogen, 20% Oxygen [about]). Heat capacity is the amount of energy required for one unit(usually a mole) of a substance's temperature to increase one degree. Since water has a higher heat capacity, it's temperature increases slower than if one was in air. Therefore making wet clothing feel cold.
F) When a wet object dries, it cools down. Through evaporation, the water turns to vapour. When the water evaporates, it takes some of the heat energy away from the clothes so you get the sensation of "coldness"
Look buddy its just of the latent heat energy of the water in different phases
A pressure cooker cooks fast because of the pressure it exerts on the food materials... due to the high pressure and high temperature water boils to cook food faster
Tea is hard to be prepared o the everest beacause of the deficiency of oxygen for combustion of firewood
Just a heads up, the beginning of your answers make you look like a jerk. However the rest is okay
Question a) This question was asked under Chemistry some time back. Below is what I thought was an excellent answer by rudi_in.
Quote:
Originally Posted by rudi_in
Why a steam burn is worse then hot water... you should know that.
omg dude i read the exact same book yhu read! im searching for the same answers! but ill try and help yhu!
B) A pressure cooker cooks food faster when you put the lid on and the pot becomes air tight. When you add the heat the warm air gets trapped in the pot having ALOT of pressure and that hotness and the pressure makes the food cook faster :)
F) Wet clothes feel cold- When you wear the wet garment the heat of your body tranfers to the material making you feel cool. :)
hope that helped? x
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