Question

A cylinder-piston system contains an ideal gas at a pressure of 1.0 × 10M5Pa. The piston is pushed in, compressing the gas from an initial volume of 0.0005 m³ to a final volume of 0.0003 m³. The system absorbs 25 J of heatduring this process. What is the change in internal energy?A. -45 JB. 5.0 JC. 45 J D. -5.0 J

Answer 1

We have:

P = pressure = 1 x 10^5 Pa

Vi = initial volume = 0.0005 m^3

Vf= final volume = 0.0003 m^3

Q = heat = 25J (absorbs)

First, calculate work (W)

W = p (vf-vi)

W= 1 x 10 ^5 Pa ( 0.0003 m^3- 0.0005 m^3)

W= - 20 J

Now, apply:

ΔU= Q - W

Where:

ΔU = change in internal energy

Replacing:

ΔU= 25J - (-20J) = 45J (option C)