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Are the gases coming out when a refrigerator is opened vapours?

Are the gases coming out when a refrigerator is opened vapours? Then why is it called?

Asked by a 7th std student.

Answer:

Air contains humidity (due to the presence of water vapour). Evaporation can take place at any temperature. However the rate of evaporation increases with increase in temperature..

The conversion of a liquid to gas can take place due to evaporation or boiling. but boiling is the phenomenon taking place at a higher but constant temperature.

Due to evaporation (and boiling) the air contains water vapour at room temperature.

When we open the fridge the water vapour condenses to tiny droplets of water and become visible (due to scattering of light).

(I feel that all the concepts might not have been cleared, please ask the questions which arise as comment to this post.)

 

Water content in our body helps to regulate temperature stable.

Does the presence of large amounts of water in the body help keep body temperature stable? exp

Water Drop

lain.

Asked  Deryn

Answer:

The answer is yes.

Here, the high value of specific heat capacity of water helps.

Drinking water helps regulating the body temperature during winter (extreme cold) as well as during summer.

I remember, schools had made it mandatory for students to dring water after every period during a summer time when the atmospheric temperature was too high and students used to faint often. The water treatment was very effective and the no. of students fainting due to high surrounding temperature decreased significantly.

If we consider the earth system also. it can be seen that the climate is moderate near water bodies.

Further, it is the abundance of water on earth which makes it a planet suitable for the existence of life.

The Physics of a Pressure Cooker

How does a pressure cooker work? What is the Physics behind it?

Answer:

Pressure Cooker
Physics of Pressure Cooker

A pressure cooker develops a very high pressure when water boils inside. At high pressure the boiling point of water also rises and therefore food gets cooked at a higher temperature. Therefore the food materials are cooked well and faster than at normal temperature and pressure.

A pressure cooker is extremely useful in hilly areas where the pressure is very low and the boiling point is less for water. AT a lower boiling point, cooking is very difficult as proper cooking will not take place. When a pressure cooker is used, it increases the pressure as well as the boiling point and the food materials can be cooked well.

Geothermal Energy

p.tejaswini asked

“Why is geothermal energy an alternative source of nuclear energy?”

There is some problem with the doubt you asked. It is correct to say “Geothermal energy and Nuclear energy are alternative sources of energy

Sun is the ultimate source of energy for earth. The energy of fuels, wind energy, water energy, food – all these are derived from sun. But Geothermal energy and nuclear energy are not derived from solar energy.

GeoThermal Energy Links for Reference

http://www.renewableenergyworld.com/rea/tech/geothermal-energy

http://www.geos.iitb.ac.in/geothermalindia/pubs/geoweb.htm

See a diagram of Geothermal plant

Geo Thermal Energy
Geo Thermal Energy

The centre of the Earth is around 6000 degrees Celsius – easily hot enough to melt rock. Even a few kilometres down, the temperature can be over 250 degrees Celsius if the Earth’s crust is thin. In general, the temperature rises one degree Celsius for every 30 – 50 metres you go down, but this does vary depending on location

In volcanic areas, molten rock can be very close to the surface. Sometimes we can use that heat.

Geothermal energy has been used for thousands of years in some countries for cooking and heating.

The name “geothermal” comes from two Greek words: “geo” means “Earth” and “thermal” means “heat”.

Read More on Geothermal Energy Here

Flow of air?

I’m working on a science project now and I have a doubt,Consider two places(A and B) with a vast temperature difference connected by a insulated pipe,would air flow through the pipe from A to B?lets say A is up in the mountains and B is in the plains,air flows from a cold place to a hot place,doesn’t it?If it does flow, I would like to know how to calculate it’s pressure.If it doesn’t flow,I would like to know the reason for that as well.

Thermal Expansion Problem

Meenu asked:

A metre scale is calibrated at 0 degree celsius to give correct reading. Find the distance between 50 cm and 51 cm if the scale is used at 10 degree celsius. Coefficient of linear expansion of steel is 1.1×10-5

Answers given in two books are 1.00011cm and 0.99988 why this contradiction?

(The question is being posted at PhysicsForum.PlusTwoPhysics.com too so that visitors can readily reply with their answers and explanations)

Atom Bomb, Hydrogen Bomb, Nuclear Bomb

Charan asked:

what is the difference between a atomic and a nuclear bomb?

Answer:

image Any bomb depending on nuclear reactions for its operation is a nuclear bomb.

Atom Bomb depends on Nuclear fusion reactions (Uncontrolled Chain reaction)

Hydrogen Bomb is a nuclear fusion Bomb, and requires an atom bomb explosion first to generate the necessary temperature for it to start working.

Both Atom Bomb and Hydrogen Bomb are nuclear bombs.

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