# Is thermal/heat energy the same thing as internal energy?

I learned that internal energy of an object is the sum of the kinetic energy and potential energy of the molecules of the object. Is this energy the same thing as the heat energy the object contains?

• For starters, heat describes a transfer of energy so it's misleading (although a common mistake) to talk about an object as "containing" heat. – Sean Dec 4 '14 at 13:00
• @Sean Too many people are focusing on his use of the word heat. He's got a very good question that people are side stepping to show that they know what heat is: Is thermal energy the same as internal energy? – Enrique Mendez Jul 5 '17 at 14:28

Internal energy is a measure of the amount of kinetic and potential energy possessed by particles in a body and is measured in Joules. Heat energy on the other hand only concerns transfer of internal energy from a hotter body to a colder body.

• Nice answer, but "transfer" would be more appropriate than "movement"! – L. Levrel Apr 24 '16 at 10:03
• In a heat pump heat flows from cold to hot. This definition is not general enough. Heat is just a transfer of energy and entropy. – boyfarrell Apr 25 '16 at 5:42

Thermal and internal energy is equal to the sum total kinetic energy possessed by the the molecules whereas the heat energy is the transfer of thermal energy from high temperature to low temperature.

• There is no such thing as "thermal energy" of an object, and internal energy does not come down to kinetic energy only. – L. Levrel Apr 24 '16 at 10:04

Saying that a body possesses heat energy is as absurd as saying it possesses work! that is work and heat are merely names given for energy transfers. when you heat an object and say heat energy is transferred, we mean that the molecules in the heated object are becoming more jiggly(vibrations) that is their kinetic energy is increasing. that is what is meant by saying that heat energy increases internal energy. internal energy on the other hand is a macroscopic property of the system that arises solely from interactions between the particles that make up the system. feel free to correct me if i am wrong and hope this helped

If two objects are placed in contact (so that energy can flow between them easily) energy will flow from the hotter to the cooler object. Energy flowing from a region of higher temperature to a region of lower temperature is called Thermal Energy. When two objects are at the same temperature, there will be no transfer of thermal energy, and we say they are in Thermal Equilibrium.

'Thermal' energy and 'Heat' energy mean the same thing. 'Internal' energy and 'Thermal' energy do not mean the same thing, but they are related. If you add Thermal Energy to a substance its Internal Energy will increase.

Internal Energy is defined as the sum of the random distribution of the kinetic and potential energies of the molecules/atoms in a substance. In order to increase either the kinetic energy, or potential energy of the molecules/atoms in a substance, you need to add Thermal Energy to the substance.

## protected by ACuriousMind♦Jul 5 '17 at 14:54

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