You are watching: Why is heat a path function
This is the extract native Halliday & Resnick.
My chem publication writes:
Heat & work-related are the creates of power in transit. They appear only once there wake up any adjust in the state that system and the surroundings. Lock don"t exist before or after the change of the state.
So, heat power is dependent on the course or the means the device changes, right? So, room they saying, for one course connecting two states, an ext heat power can be liberated if for one more path, less warm is released? How? for the same two states, how deserve to there it is in a various amount that heat energy liberated? Is there any intuitive instance to recognize this?
improve this inquiry
edited Jun 7 "18 in ~ 9:12
cutting board Lee Abshier ND
80411 yellow badge99 silver badges1414 bronze badges
asked Nov 17 "14 at 12:24
include a comment |
5 answers 5
energetic earliest Votes
Think the it prefer this. As soon as you have an object of fixed $m$ which is hosted a height $h$ above some referral point, you think of it as having actually potential energy (considering only gravitational interactions) $U= m g h$, and also gravity will certainly exert an quantity of work-related $W_g = m g h$ on the object. When you drop the object, the shall loss towards the ground, towards “equilibrium”, so to speak. You do not speak the the quantity of “work” that the mass has when in ~ its initial height, nor of the amount of “work” lost, but of its power (relative come a reference point) at any kind of given state, $U$. Moreover, we say the this potential power is a state function because it relies only ~ above the initial and also final heights that the fixed in question.
See more: What Clogged The Toilet On Jersey Shore, Who Clogged The Toilet On Jersey Shore
In the exact same way, one go not problem his or her self v the quantity of “heat” that an object has, because it is simply a term used to denote the amount of moved energy between systems together they move in and also out of equilibria. We speak of thermal energy, inner energy, free energies and also such that space state attributes of the mechanism - in precisely the same way that the gravitational potential energy $U$ remained in the mechanical analogue come this thermodynamical case. In the same way, we say that the thermal energy of the mechanism is a state role insofar the it normally depends (more or less) top top the initial and also final temperatures and thermodynamic quantities of the fixed in question.
Edit: i’ve reread her question and also I desire to do another allude to clear points up. Yes, indeed, various paths can an outcome in different amounts of warmth transfer - the first law of thermodynamics states:
$\delta E = Q + W$,wherein $Q$ is the amount of heat circulation into the system, $W$ is the work done top top the system, and also $\delta E$ is the full state interior energy adjust of the system. One have the right to see that one deserve to input say, 100 J of heat and also do no occupational on a system to an outcome in a net change $\delta E$ the 100 J, and also in the very same way, one deserve to divide that $100 J$ among $W$ and also $Q$ to gain the exact same effect.
The intuition is as follows. Imagine you have actually a seasoned of gas. You deserve to increase the temperature (and so send a positive $\delta E$) by including $100 J$ of heat, or you may compress that by doing $100 J$ of job-related to get the exact same effect. I hope that gets rid of things up!