Thermodynamics and Heat Transfer Quiz

In thermodynamics, heat is the thermal energy transferred between systems due to a temperature difference. In colloquial use, heat sometimes refers to thermal energy itself. Thermal energy is the kinetic energy of vibrating and colliding atoms in a substance. An example of formal vs. informal usage may be obtained from the right-hand photo, in which the metal bar is 'conducting heat' from its hot end to its cold end, but if the metal bar is considered a thermodynamic system, then the energy flowing within the metal bar is called internal energy, not heat.

The hot metal bar is also transferring heat to its surroundings, a correct statement for both the strict and loose meanings of heat.

Another example of informal usage is the term heat content, used despite the fact that physics defines heat as energy transfer. More accurately, it is thermal energy that is contained in the system or body, as it is stored in the microscopic degrees of freedom of the modes of vibration.

<p>Heat is energy in transfer to or from a thermodynamic system by a mechanism that involves the microscopic atomic modes of motion or the corresponding macroscopic properties. This descriptive characterization excludes the transfers of energy by thermodynamic work or mass transfer.</p> Signup and view all the answers

<p>Defined quantitatively, the heat involved in a process is the difference in internal energy between the final and initial states of a system, and subtracting the work done in the process.</p> Signup and view all the answers

<p>The thermal energy transferred between systems due to a temperature difference</p> Signup and view all the answers

<p>Thermal energy itself</p> Signup and view all the answers

<p>'The hot metal bar is transferring heat to its surroundings'</p> Signup and view all the answers

<p>'Thermal energy contained in the system or body'</p> Signup and view all the answers

<p>'Transfers of energy by thermodynamic work or mass transfer'</p> Signup and view all the answers