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Answers to Readers' Questions on Physics:
Pressure and States of Matter
List of first 10 items
- Pressure and area
- How much does water expand when it turns to steam?
- What state of matter is a cloud?
- How many times does water expand?
- Process of solid changing into gas
- Which water freezes first?
- Compressing air to an extreme
October 22, 2010
hallow can I ask a question 1) Is pressure depend on area if yes why we say that pressure depend on 1- height 2- density of material as pressure is height times density times accelration due to gravity for aliquid 2) why pressure of the foot of human is greater than pressure of elephant's heel althouh pressure act on a unit area not surfaca area? I hope you help me
esraa - Egypt
Pressure is the force divided by the area that the force is applied. The force can be the weight of a solid object or a fluid.
The height of a fluid or liquid increases its weight and thus its pressure at that depth.
The pressure applied by a man's foot can be greater than the pressure of the foot of an animal 10 times as heavy, provided that the area of the animal's foot on the ground is greater than 10 times the area of a man's foot.
August 27, 2009
How many times does water expand when it turns to steam? I say 1600 a friend of mine says 1728
Dean - Canada
At atmospheric pressure, the expansion ratio between liquid water and steam is about 1:1700.
Of course, it depends on at what temperature you start also, but it is a good approximation.
May 5, 2007
In what state of matter is A CLOUD on the sky
Is it liquid or gas or a mixture whatever ?
denis - GREECE [HELLAS]
A cloud is typically the gaseous state of water. But often tiny water droplets can form within a cloud, especially just before it starts to rain. In same cases, solid ice particles can form in a storm cloud, resulting in hail.
So, a cloud is usually a gas, but it can be a mixture under certain circumstances.
October 18, 2006
How many times does water expand when it turns to steam?
Yamile - USA
Water expands when heated. When it turns to steam, the steam itself expands.
October 11, 2006
Dear school for champions I like your site and all but I asked what is the process of solid changing into gas and didnt get an answer leaving me to continue my search so if you please add this answer to your site I would really appreciate it. Also I noticed that you didnt mension the process of evaporation heat of fusion or any of those things so I think you should also add all the things like that.
- United States Virgin Islands
Sorry taking so long to answer you. We've had too many email lately.
Our lesson on Changing States of Matter shows how changing a solid to a gas is called sublimation.
In Pressure and States of Matter, the chart shows that when the pressure and temperature is low, the material will skip the liquid phase and go directly from a solid to a liquid. For example, at very high altitudes (low air pressure) ice can go directly to become steam.
We may cover evaporation heat of fusion some time soon.
August 17, 2006
when you put cold water and hot water in an ice tray, which one freezes faster?
joanie - USA
Usually the cold water freezes faster, but there are exceptions. See our lesson on the Mpemba Effect at: http://www.school-for-champions.com/science/mpemba.htm
April 3, 2006
1. Is it possible to compress air till it reaches 1000kg/m3.(ie. water density).?Please justify the answer.
2.What is the maximum pressure and temperature attained before there is a phase change into water?
KALYANAKUMAR - INDIA
When air is compressed and liquefied, it can reach water density. For example, liquid Nitrogen has a density of 800kg/m^3.
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