SfC Home > Physical Science > Physics >

Reader questions and feedback on Physics. Also refer to physical science, chemistry, astronomy, electricity, magnetism, electromagnet, light, sound, waves, forces, work, energy, friction, heat, thermodynamics, Ron Kurtus, School for Champions. Copyright © Restrictions

Answers to Readers' Questions on Physics:

Pressure and States of Matter

The following 8 comments and questions have been sent in. They are listed according to date.

List of first 10 items

Next 10

Volume at the change in state


July 27, 2014

1. As the temperature raises and the matter changes from solid to liquid, then liquid to gas. How does the amount of space that the matter is taking uo change?

2.. As the temperature lower and the matter changes from solid to liquid, then liquid to gas. How does the amount of space that the matter is taking uo change?

Mary jane - Philippines



Typically, the volume of the material increases as it changes from solid to liquid and liquid to gas. However, the volume of water is slightly less than ice at 0 degrees C until 3 degrees, when it starts to expand.

Water is one of the few materials that expands when it turns to a solid (ice).

Back to top

Pressure and area


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.

Back to top

How much does water expand when it turns to steam?


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.

Back to top

What state of matter is a cloud?


May 5, 2007

In what state of matter is A CLOUD on the sky
Is it liquid or gas or a mixture whatever ?
thank you




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.

Back to top

How many times does water expand?


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.

Back to top

Process of solid changing into gas


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.
See: http://www.school-for-champions.com/science/matterstates_changing.htm

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.

Back to top

Which water freezes first?


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

Back to top

Compressing air to an extreme


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?




When air is compressed and liquefied, it can reach water density. For example, liquid Nitrogen has a density of 800kg/m^3.

Back to top

Next 10


Hopefully, this reader feedback has helped provide information about Science issues.

Look toward your future


The following are some resources on this topic.


Physics Resources


Top-rated books on Physics

What do you think?

Do you have any questions, comments, or opinions on this subject? If so, send an email with your feedback. We will try to get back to you as soon as possible.

Feel free to establish a link from your website to pages in this site.

Where are you now?

School for Champions

Physical Science Topics

Answers to Readers' Questions

Live Your Life as a Champion:

Take care of your health

Seek knowledge and gain skills

Do excellent work

Be valuable to others

Have utmost character

Be a Champion!

The School for Champions helps you become the type of person who can be called a Champion.