SfC Home > Physical Science >

Reader questions and feedback on physical science. Also refer to physics, 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 Physical Science:

Heat

The following 42 comments and questions have been sent in. They are listed according to date.

List of first 10 items

• Why do the floorboards creak at night?
• What is the value of thermal energy
• How does heat move along an iron rod?
• Does Earth's core cause global warming?
• Why are tropical areas more humid?
• Why do we get hot?
• Calculating the specific latent heat of steam
• Why is the freezer compartment at the bottom?
• Why is the freezer compartment at the top?
• How does heat affect different chemicals?

Next 10

Why do the floorboards creak at night?

Question

October 1, 2009

why do the floorboards creak at night when heat is turned off? why is water not used as a liquid in thermometers?

moll - Ireland

18419

Answer

Wood expands when heated and contracts when it cools. A tight fit of the wooden boards can cause creaking as it changes size. You notice the creaking more in the quiet of the night than in the daytime.

Water freezes at 0 degrees C, so it would not be useful to measure temperatures outside in the winter. They rather use red-colored alcohol in most thermometers, because it can be used at many temperatures.

Back to top

What is the value of thermal energy

Question

September 8, 2009

Consider an object with 100 degree celcius ,then what is the value of thermal energy ..?

KARTHIK - India

18280

Answer

See Thermal Energy is Total Kinetic Energy at:

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

Back to top

How does heat move along an iron rod?

Question

June 13, 2009

HOW HEAT MOVES FROM ONE POINT OF AN IRON ROD TO ANOTHER

GOKULESAN - India

17902

Answer

When you heat an iron rod, you are giving its molecules energy and causing them to move faster. The high energy or faster molecules bump into nearby low energy iron molecules, causing them to move faster. In this way, the heat moves along the iron rod from the hot or high energy end to the cool or low energy end.

Back to top

Does Earth's core cause global warming?

Question

May 6, 2008

Does radiation from the Earth's cores causes global warming?

Nuria - USA

15877

Answer

The Earth's core is very hot and does have some effect on the temperature above ground. But the major cause of global warming is the trapping of infrared radiation from the Sun. See: Infrared, Gases and the Greenhouse Effect at http://www.school-for-champions.com/science/infrared_greenhouse_effect.htm for more information.

Back to top

Why are tropical areas more humid?

Question

March 28, 2008

why does warm rise?

why are coastal tropical areas more humid than desert areas?
How does topography contribute to the formation of desert areas? what role do the Sierra Nevada mountains have in keeping the Nevada desert?

Florine - USA

15620

Answer

Molecules move faster in warm air, causing it to expand and be less dense than cool air. Less dense air rises.

Coastal areas have much more rain than desert ares, thus the air is more humid. Mountains often prevent rain from reaching desert areas.

Back to top

Why do we get hot?

Question

March 6, 2008

I wonder what is a magnetic field when it is close to heat. By the way what makes up heat other than the sun?I just wonder because sometimes I feel very hot when it is cold out. I hope you can answer my tough question, bye
(age:10)

Torry - USA

15495

Answer

Although a magnet will lose its power when it is heated up, a magnetic field itself is not affected by heat.

Heat or thermal energy is caused by the rapid movement of atoms or molecules. The faster they move, the hotter the material. The sun, fires, and light bulbs are some sources of heat.

Your body creates heat through the chemical reactions of food and oxygen. When you exercise, your body creates more heat. That is why you can even sweat when exercising on a cold day.

Back to top

Calculating the specific latent heat of steam

Question

November 16, 2007

the page is very helpful.
i have spent the whole night solving one complex question still i have proved failure.can any one help me how to solve the following question? tin contains water at 290k and is heated at a constant rate and is observed that the water reaches boiling point after 2 minutes and after further 12 minutes it is completely boiled away calculate the specific latent heat of steam.

waiting hearing from you

- Tanzania

14788

Answer

Some of the information in the question is not necessary to solve the problem. See the lesson on Heat Required to Turn Ice into Steam at:
http://schoolforchampions.com/science/heat_ice_steam.htm

It gives an explanation and the numbers needed.

Back to top

Why is the freezer compartment at the bottom?

Question

March 12, 2007

Why are some of the freezer compartment at the bottom? How do they work? Is it still as efficient as the one with the freezer on the top?

Lim - Singapore

13350

Answer

Originally, refrigerators used ice to cool them. The freezer was placed at the top because ice was placed there. The cold air then slowly flowed to cool lower part of the refrigerator.

But modern refrigerators have a sealed freezer and separate cooling. It is as efficient whether the freezer is at the top or the bottom. The major reason some refrigerators have the freezer on the bottom is that it is more convenient. People do not go in and out of the freezer as often as the main part of the refrigerator. It only make sense to have the area you use the most at the top, where you can reach things easily.

Back to top

Why is the freezer compartment at the top?

Question

June 19, 2006

why is the freezer compartment at the top in a refrigerator and why is the element at the bottom in an electric kettle?

- USA

11355

Answer

Some freezers are on the side and a few refrigerators have them on the bottom. The placement seems to be the preference of the people using refrigerators. Perhaps they feel it is more convenient to ahve the freezer on the top.

Heated water rises to the top. Having the heater element on the bottom results in the water circulating and convection transfer of heat energy. The water wamrs faster.

Back to top

How does heat affect different chemicals?

Question

December 23, 2005

How does heat affect different chemicals?

why does Hot vinager and salt work better at cleaning a penny than room tempature of cold vinager or salt?

Gace - USA

9457

Answer

Most chemcial reactions work better at higher temperatures because the molecules are more active and have more energy. Some chemicals required very high temperatures to cause a reaction.

Back to top

Next 10

Summary

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

Resources

The following are some resources on this topic.

Websites

Science Resources

Books

Top-rated books on Physical Science

Miscellaneous

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 can you go from here?

School for Champions

Physical Science Topics

Answers to Readers' Questions