233k views
1 vote
A gas in a piston-cylinder assembly undergoes a process for which the relationship between pressure and volume is pV2= constant. The initial pressure is 1 bar, the initial volume is 0.1 m3, and the final pressure is 9 bar. Determine the work for the process.

1 Answer

4 votes

Based on the available information, the work for the process is approximately -30,030 Joules. The negative sign indicates that work is done on the system.

To determine the work for the process, we can use the formula for work done in a piston-cylinder assembly:

W = ∫(PdV)

Given that the relationship between pressure and volume is pV² = constant, we can rewrite it as:

P = k / V²

where k is the constant.

To find the value of k, we can use the initial conditions:

P1 = 1 bar = 100,000 Pa

V1 = 0.1 m^3

Substituting these values into the equation, we get:

100,000 = k / (0.1)²

k = 100,000 * (0.1)²

k = 100,000 * 0.01

k = 1,000

Now, we can express the pressure as a function of volume:

P = 1,000 / V²

To calculate the work, we integrate the expression for work:

W = ∫(PdV) = ∫((1,000 / V²)dV)

Integrating this expression, we get:

W = -1,000 / V

To find the limits of integration, determine the final volume (V2) corresponding to the final pressure:

P2 = 9 bar = 900,000 Pa

Substituting this value into the equation, we get:

900,000 = 1,000 / V2²

V2² = 1,000 / 900,000

V2² = 0.001111...

V2 ≈ 0.0333 m³

Now, we can calculate the work:

W = -1,000 / V

W = -1,000 / 0.0333

W ≈ -30,030 J

Therefore, the work for the process is approximately -30,030 Joules. The negative sign indicates that work is done on the system.

User Dodov
by
7.8k points