# Need help ly

1. Mar 22, 2008

### junec21

Question ...

i have problem with these 2 questions.i been cracking my head the whole day about this/ anyone please help. please write down the steps for me if possible. thanks a lot in advance.

1) 0.25 kg of combustion gas in a diesel engine cylinder is at temperature of 727°C. The gas expands at constant pressure until its volume is 1.8 times its original value. For the combustion gas, R = 0.302 kJ/kgK and Cp = 1.09 kJ/kgK. Find the following:
a) temperature of the gas after expansion
b) heat transferred
c) work transferred

2) A quantity of gas has an initial pressure and volume of 0.1 MN/m2 and 0.1 m3, respectively. It is compressed to a final pressure of 1.4 MN/m2 according to the law pV1'26 = constant. Determine the final volume of the gas.

Last edited: Mar 22, 2008
2. Mar 22, 2008

### Hootenanny

Staff Emeritus
Hi Junec & welcome to PF,

What have you attempted thus far?

3. Mar 22, 2008

### rock.freak667

a)If you know it expands at constant pressure....What does that mean for Volume and Temperature? (Check what Charles's law says about it)
b)What is the definition of $C_p$?
c) Do you know a formula for finding the Work done by a gas when it expands its volume at a constant pressure?