Question

A cylinder of gas is compressed by a piston from an initial volume of 125 liters to a final volume of 90 liters. The compression occurs at constant pressure, and the work done on the gas by the piston is 104 joules. What is the gas pressure during the compression? (1 liter = 10-3 meters3)

Answer 1

Since the process occurs at constant pressure, the work done by the gas on the piston is given by
$W=p \Delta V = p (V_f - V_i)$
where
W is the work
p is the pressure
$V_f$ is the final volume
$V_i$ is the initial volume

In our problem, we have
$V_i =125 L = 125 \cdot 10^{-3}m^3$
$V_f = 90 L = 90 \cdot 10^{-3} m^3$
$W=-104 J$ (where the negative sign means the work is done by the piston on the gas)

We can re-arrange the previous equation and use these values to find the pressure:
$p= \frac{W}{V_f - V_i}= \frac{-104 J}{90 \cdot 10^{-3} m^3 - 125 \cdot 10^{-3} m^3}=2971 Pa$

Answer 2

Answer: 3 x 10^5 pascals

Explanation: I think you meant to put 10^4 joules instead of 104, which is why nobody likes the previous answer, using 10^4 joules gets you. the answer with the following:

Using the same equation the person above me posted....

 -10^4/(90E-3-125E-3) And then only one significant figure from the question and we round to 3 x 10^5 pascals