# B Question of temperature

1. Dec 31, 2016

### Clara Chung

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?

2. Dec 31, 2016

### Andrew Mason

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.
Yes. Temperature difference always determines the direction of heat flow.
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

Last edited: Dec 31, 2016
3. Dec 31, 2016

### jbriggs444

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.

4. Dec 31, 2016

### Clara Chung

I have figured out the questions. Thanks for all your help