# Homework Help: Heat Engine

1. Jan 28, 2014

### Cwhitlatch32

1. The problem statement, all variables and given/known data

a heat engine draws 200J of heat from the hot reservoir at 400K produces 110J of useful work and dumps 90J into the cold reservoir at 200K could this engine be built why or why not?

2. Relevant equations

PV=NkbT

3. The attempt at a solution
Not Sure on how I would set this equation up to figure out an answer
N(1.38x10^-23(273K).... Need direction in the right path..

2. Jan 28, 2014

### Staff: Mentor

Have you learned about Cauchy's inequality? What is the change in the entropy of the engine over the cycle? What is the sum of the Q/T's?

3. Jan 28, 2014

### Cwhitlatch32

I do not believe so, And what is the sum of the Heat and Temperatures? Is that what you are asking?

4. Jan 28, 2014

### Staff: Mentor

What kind of course does this question come from?

5. Jan 28, 2014

### Cwhitlatch32

Gen Physics 2, it is Physics 222

6. Jan 28, 2014

### Andrew Mason

Another slightly different approach: What is the efficiency of the most efficient engine possible? What is the efficiency of this engine?

AM

7. Jan 29, 2014

### Staff: Mentor

Is it correct to say that you are currently covering some aspects of Thermodynamics, and one of the things you are studying is the Second Law and Entropy? Have they used and defined the term entropy yet?

Chet