Homework Help: Pressure from compression

1. Jun 3, 2010

ghostbuster25

a sample of an idel monotomic gas is intially at a pressure 1.6*10^4Pa and undergoes an adiabatic compression which halves the volume. What is the final pressure?

ive been trying to find a way of useing the equation W=-P$$\Delta$$V but am starting to think this is the wrong one as i cant see how i can use it.

any suggestions?

2. Jun 3, 2010

ehild

Find the relation between pressure and volume of an ideal gas during an adiabatic process.

ehild

3. Jun 3, 2010

ghostbuster25

sorry i cant see it :(,

i can only see that p*V= a constant but not sure how to use that here!

am i way off track?

4. Jun 3, 2010

5. Jun 3, 2010

ghostbuster25

im still unclear on the relationship after reading that

6. Jun 3, 2010

rock.freak667

Last edited by a moderator: Apr 25, 2017
7. Jun 3, 2010

ehild

The mathematical equation for an ideal fluid undergoing a reversible (i.e., no entropy generation) adiabatic process is

$$P V^{\gamma} = \operatorname{constant} \qquad$$

where P is pressure, V is volume, and

$$\gamma = {C_{P} \over C_{V}} = \frac{\alpha + 1}{\alpha}$$,

CP being the specific heat for constant pressure, CV being the specific heat for constant volume, γ is the adiabatic index, and α is the number of degrees of freedom divided by 2 (3/2 for monatomic gas, 5/2 for diatomic gas).

ehild