The discussion clarifies the relationship between energy and work in thermodynamics, emphasizing two definitions: the mechanical definition, where work is defined as "work = force x distance" (f.d.), and the thermodynamic definition, which states that "work is a transfer of energy other than through heat." The latter is utilized in Lagrangian and Hamiltonian mechanics, where energy is defined as the conserved quantity associated with time invariance of the Lagrangian. The conversation highlights the distinction between organized energy transfer (work) and disorganized energy transfer (heat).
PREREQUISITESStudents and professionals in physics, particularly those studying thermodynamics, mechanical engineering, and anyone seeking to understand the fundamental concepts of energy transfer and work in various physical theories.
hwall95 said:Okay i know that energy is the ability or capacity to do work. But how do you define work, as like the isn't work just the transference of energy in one form to another? Which is kinda circular reasoning. Like the rely on each other for a definition. Is that right?
DaleSpam said:The appropriate definition of work depends on what theory you are using.
One is the mechanical definition: "work is f.d". This definition is used in basic Newtonian mechanics. In it forces are the primary things and everything else is defined based on forces. Then energy is non-circularly defined as the capacity to do work.
The other is the thermodynamic definition: "work is a transfer of energy other than through heat". This definition is used in Lagrangian and Hamiltonian mechanics as well as all field theories. In these, the Lagrangian is the primary thing and everything else is defined based on the Lagrangian. Then energy is non-circularly defined as the conserved quantity associated with time invariance of the Lagrangian.
No, that is just the definition of work in thermodynamics. Energy can be transferred between systems either through heat, or through anything else. Anything else is called work.hwall95 said:hahah yeah thanks i was meaning the thermodynamics definition sorry, okay thanks but when you say "other then heat energy", is that because thermal energy itself is just kinetic energy?
DaleSpam said:No, that is just the definition of work in thermodynamics. Energy can be transferred between systems either through heat, or through anything else. Anything else is called work.
The basic distinction is that heat is a rather disorganized microscopic transfer that you cannot see in detail, as opposed to things like macroscopic fields and forces.