Can Temperature Be Misleading in Energy Comparisons?

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Temperature, as a measure of average translational kinetic energy (KE), does not solely determine a system's internal energy, which includes both kinetic and potential energy contributions. Energy can flow from a higher temperature object to a lower temperature object, even if the latter has greater internal energy, as heat transfer is dictated by temperature differences. The molecular potential energy (PE) refers to the energy associated with intermolecular forces, which can decrease when molecules are compressed closer together. For example, a large block of ice has more internal energy than a small candle flame, despite the flame having a higher temperature. Understanding these concepts is crucial for accurate energy comparisons in thermodynamics.
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1.If temperature is just a measurement of KE, can a system with higher temperature contains lower internal energy than a system with lower temperature?
2.Can energy flow from an object with higher temperature to an object with lower temperature even if the internal energy of the object with a lower temperature is higher?
3. It is said that the gas passing through compressor will result in decrease on its molecular PE, what does molecular PE refer to?
 
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Clara Chung said:
1.If temperature is just a measurement of KE, can a system with higher temperature contains lower internal energy than a system with lower temperature?
Yes. Temperature is a measure of the average translational KE of the molecules in the system. Internal energy is the sum of the KE (all modes, translational, rotational, vibrational) + the total PE of all molecules in the system. Internal energy is a function of the number of molecules and the average KE and PE of its molecules. Temperature is just a function of the average translational KE per molecule.
2.Can energy flow from an object with higher temperature to an object with lower temperature even if the internal energy of the object with a lower temperature is higher?
Yes. Temperature difference always determines the direction of heat flow.
3. It is said that the gas passing through compressor will result in decrease on its molecular PE, what does molecular PE refer to?
If there are inter-molecular attractive forces (such as in water), there will be molecular potential energy. A decrease in the average separation distance between molecules will reduce the average potential energy of the molecules.

AM
 
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Clara Chung said:
1.If temperature is just a measurement of KE, can a system with higher temperature contains lower internal energy than a system with lower temperature?
Temperature is not just a measurement of KE, though KE per degree of freedom is a close approximation under many conditions.

A huge block of ice contains more internal energy than a tiny candle flame.
2.Can energy flow from an object with higher temperature to an object with lower temperature even if the internal energy of the object with a lower temperature is higher?
Heat will flow from candle flame to ice block.
 
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jbriggs444 said:
Temperature is not just a measurement of KE, though KE per degree of freedom is a close approximation under many conditions.

A huge block of ice contains more internal energy than a tiny candle flame.

Heat will flow from candle flame to ice block.
I have figured out the questions. Thanks for all your help
 

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