17 - system its internal energy will decrease . 17.4.3....

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
17.4.1. Adiabatic Processes If a system is well insulated, no transfer of heat will occur between it and its environment. This means that Q = 0, and the first law of thermodynamics shows that AEU = - W If work is done by the system (positive W) its internal energy decreases. Conversely, if work is done on the system (negative W) its internal energy will increase. For gases, the internal energy is related to the temperature: a higher internal energy means a higher temperature. Adiabatic expansion of a gas will lower its temperature; adiabatic compression of a gas will increase its temperature . 17.4.2. Constant Volume Processes If the volume of a system is held constant, the system can do no work (W = 0 J). The first law of thermodynamics then shows that AEU = Q If heat is added to the system its internal energy will increase; if heat is removed from the
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: system its internal energy will decrease . 17.4.3. Cyclical Processes Processes which, after certain interchanges of heat and work, are restored to their initial state are called cyclical processes. In this case, no intrinsic properties of the system are changed, and therefore AEU = 0. The first law of thermodynamics now immediately yields Q = W 17.4.4. Free Expansion Free expansion is an adiabatic process in which no work is done on or by the system. This means that Q = W = 0 J, and the first law of thermodynamics now requires that AEU = 0 J 17.5. Transfer of Heat The transfer of heat between a system and its environment can occur in a variety of ways. Three different mechanisms of heat transfer will now be discussed: conduction, convection, and radiation....
View Full Document

This document was uploaded on 11/25/2011.

Ask a homework question - tutors are online