List of Topics

SfC Home > Physics > Thernal Energy >

 

Feedback Comments on Thermal Energy

by Ron Kurtus

A total of 374 comments and questions have been sent in. They are listed according to date.

You can read them to further your understanding of the subject.



List of next 10 letters

Topic

Title

Country

Heat Transfer on Earth Will the Earth slow down from global warming? India
 
Heat Why does hot chocolate go cold? Australia
 
Heat Transfer What reduces heat loss by radiation? Nigeria
 
Thermal Insulation Want to know if I'm making a thermos correctly Canada
 
Thermal Insulation What factors determine the compressor to use? Kenya
 
Thermal Insulation We have to build a thermos Canada
 
Thermal Energy Thermal, internal and kinetic energy relationship USA
 
Thermal Insulation Radiation and conduction from a black body material USA
 
Heat Transfer Is it possible to fry an egg on the sidewalk? USA
 
Thermal Energy Thermal energy and cups of coffee USA
 

Next 10

 




First 10 letters


Will the Earth slow down from global warming?

Topic: Heat Transfer on Earth

Question

June 15, 2010

Due to increse in tempeture there is effect on earth revulation (May be some few scecond )

sam - India

19906

Answer

It is possible that the rotation of the Earth will slow down due to global warming if the ice at the poles starts to melt. The added water will produce extra friction on the rotation of the Earth, thus slowing it down a small amount.

Back to top


Why does hot chocolate go cold?

Topic: Heat

Question

June 2, 2010

I have an assignment to do about :
Why does hot chocolate go cold? i have almost finished everything but
i need more information on the Background.
Thank you very much
feel free to send me emails

Daria - Australia

19827

Answer

Anything that is warm or hot cools off until it is room temperature. A rule of thermodynamics is that temperatures average out to that of the surroundings.

Back to top


What reduces heat loss by radiation?

Topic: Heat Transfer

Question

May 18, 2010

what is the essential factor that reduces heat loss by radiation in a thermos flask?

Efex - Nigeria

19740

Answer

A thermos flask that is made of glass will allow radiation from its hot contents to escape. One method to reduce this heat loss is to wrap the glass in some shiny material, such as aluminum foil, to reflect the heat radiation or infrared radiation back into the contents. If you look into a thermos flask that his glass lined, you will often see the shiny material used to reflect the heat back into the contents.

Note that the reflective material is not a good insulator for conductive heat transfer.

Back to top


Want to know if I'm making a thermos correctly

Topic: Thermal Insulation

Question

May 11, 2010

I am making a thermos and I have a glass bottle around it is aluminum foil and over that is bubble wrap and another coat of styrofoam. Then at the bottom of the thermos is stryofoam and all around the thermos is duct tape. My question is the insolator there or in the right place? PLEASE REPLY I NEED HELP

Project due - MAY,12TH, 2010

- Canada

19705

Answer

It sounds like you have done a good job. Don't forget to insulate the cover too.

Try it out by putting in some hot water to see how long it takes to cool down. Or you can put in some ice cubes to see how long they stay frozen.

Best wishes in your project.

Back to top


What factors determine the compressor to use?

Topic: Thermal Insulation

Question

April 9, 2010

What factors determine the compressor to use in a refrigerator desighn.
Do compressors have specific climatic conditions for use.

Kim - Kenya

19520

Answer

I'm sorry, but we do not have that information available.

Best wishes in finding your answer.

Back to top


We have to build a thermos

Topic: Thermal Insulation

Question

March 23, 2010

We have to build a thremos, and I was wondering how I could make the lid of the thermos. What materials must I use, and how do I make it?

S - Canada

19423

Answer

See the lesson on Thermos at:
http://www.school-for-champions.com/science/thermos.htm

Also, look at the Reader Feedback on the page to see what other students have done.

Back to top


Thermal, internal and kinetic energy relationship

Topic: Thermal Energy

Question

March 22, 2010

what is the relationship between thermal,internal, and kinetic energy?
Are objects that have kinetic energy, hot?
anything that moves has heat?
if you say that thermal energy is the total kinetic energy of a substance why dont you say the same thing for sound when sound is alos a type of kinetic energy?

- USA

19410

Answer

The thermal energy of an object is its total kinetic energy. Some sources say that thermal energy and internal energy are the same, while other sources include potential energy--such as chemical potential--in the internal energy.

The greater the kinetic energy of the atoms or molecules in a material, the hotter the material is. This is especially seen in a gas.

Heat is the transfer of thermal energy from one object to another.

Sound is a vibration form of kinetic energy. High frequency sound waves can heat up a material. However, in normal situations, its contribution to the thermal energy of an object or material is small and often neglected.

Back to top


Radiation and conduction from a black body material

Topic: Thermal Insulation

Question

February 25, 2010

Case A: If a perfect vacuum exists between two, non-touching, "black bodies" that are at uniform but different temperatures, heat transfer between the bodies can only occur via radiation. Integrating Planck's law over all frequencies (zero to infinity) and including the Lambertian nature of black-body radiation from a planar surface (i.e., the radiation into a solid angle is proportional to the COSINE of the angle the solid angle direction makes with the normal to the black-body surface), provided two differential unit areas (one on each body) have line-of-sight visibility, one can generate a formula for the net power radiated between a differential unit of area on one black body to a differential unit of area on the other black body. By applying this formula over the entire surface areas of both bodies, one can in principle generate a formula for the heat flow between the two bodies. Suppose by hook or by crook we correctly generate such a formula.

Case B: Now fill the "vacuum of space" that existed between the two black bodies with a fixed material such as concrete. The fixed material will support heat transfer between the bodies via conduction but not convection. The formulas for conduction heat flow and radiation heat flow between two bodies are different. However, assume again by hook or by crook we can generate a formula for the conductive heat transfer between the bodies.

My question is this: To compute the "Case B" total heat transfer, do we algebraically sum (i) the "vacuum" radiative heat transfer formula of Case A...and... (ii) the conductive heat transfer formula of Case B? Put another way, when the vacuum is filled with a non-convective substance, are the radiative heat transfer properties affected by the substance? The follow-up question is: "If the radiative heat transfer properties are different for "vacuum" versus "fixed substance" conditions, how should the radiative transfer formula be modified?

Thank you for your time,

Reed - USA

19292

Answer

What this comes down to is the question of whether there is any radiation heat transfer between two materials in contact to add to the conduction heat transfer.

Conduction is caused by molecules in one material striking molecules in the other, transferring kinetic energy. However, the black body molecules are also emitting radiation, which is also providing thermal energy to the concrete material.

Neither the conduction heat transfer from a black body material to concrete nor the radiation heat transfer is very efficient. I'm not sure which is more efficient. I assume the total heat transfer would be the total of the two.

The black body emits radiation independent of the other material. However, the loss of energy due to conduction would lower the temperature of the balk body and reduce the amount and form of its radiation.

Back to top


Is it possible to fry an egg on the sidewalk?

Topic: Heat Transfer

Question

February 13, 2010

Is it possible to fry an egg on the sidewalk on a hot day?

Joseph - USA

19213

Answer

If the sun has been shining on the sidewalk, the egg would start to fry and barely get firm. However, frying an egg on the hood of a black car in the sun would work much better.

Back to top


Thermal energy and cups of coffee

Topic: Thermal Energy

Question

February 13, 2010

1. would you recieve the same amount of thermal energy if a friend was drinking a 32oz cup of hot coffee and you were drinking an 8oz cup of coffee?

amanda - USA

19212

Answer

Thermal energy is the total amount of heat or kinetic energy. A large container or warm coffee could have the same amount of thermal energy as a small container of hot coffee. However, if they were at the same temperature, the large container would have more total energy.

Back to top

Next 10


Summary

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


Do your best


Resources and references

The following are some resources on this topic.

Websites

Physics Resources

Books

Top-rated books on Thermal Energy


Questions and comments

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


Where are you now?

School for Champions

Physics topics

Thermal Energy Feedback Comments




Motion topics

Work and Energy topics



Let's make the world a better place

Be the best that you can be.

Use your knowledge and skills to help others succeed.

Don't be wasteful; protect our environment.

You CAN influence the world.




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.