# Thermodynamics - Carnot Cycle

## Homework Statement

I don't understand the process between the points in a carnot cycle.

## Homework Equations

Can someone please explain what is going on from point to point in terms of Q (heat), U(thermal energy), and Work?

## The Attempt at a Solution

Andrew Mason
In the higher temperature isothermal part, heat flows into the system. Since it is isothermal, there is no change in U so $\Delta Q = W$ (expansion-positive work done by the system). In the cooler isothermal part heat flows out of the system with no change in U so work must be done on the system (compression). Of course in the adiabatic parts there is no heat flow so the work done + the change in internal energy = 0: $\Delta U = -W$.