# Plz help (i have a paper tomorrow & i am not able to solve it)

1. Oct 4, 2005

### mohdfasieh

Plz help plz (i have a paper tomorrow & i am not able to solve it)

QUESTION :

A piston cylinder device contains 1.2 kg of nitrogen gas at 120 kpa and 300 kelvin. the gas is now compressed slowly in a polytropic process during whivh PV ^1.3=constant .The process end when the volume is reduced by one-half. Determine the entropy change of nitrogen during the process.

2. Oct 4, 2005

### Staff: Mentor

Please write the equations that you think you should be using, e.g. equation for work on/by the system.

$$\Delta S$$ = $\int_i^f\,\frac{dQ}{T}$

and the first law of thermodynamics for a closed system is

Q = $\Delta U$ + W

Last edited: Oct 4, 2005
3. Oct 4, 2005

### enigma

Staff Emeritus
mohdfasieh, please show what you've attempted, even if it's only that you looked up the equations to use.

Neither you nor we will benefit from any of us just doing your homework for you.

That being said, I'm moving this thread to Homework help.