A fixed mass of helium gas is made to undergo a process in which its pressure varies linearly from 1 kPa to 2 kPa, in relation to its volume as the latter varies from 0.2 m3 to 0.4 m3. The heat absorbed by the gas will be :
Answer & explanation
Correct answer: option 3
\(\Delta W = \frac{1}{2} (1 + 2) * 10^3\) N/m2 x (0.4 - 0.2) m3
= 300 J
\(\Delta U = n C_v \Delta T\)
= \(\frac{P_2V_2 - P_1V_1}{\gamma - 1}\)
\(\Rightarrow \Delta U = \frac{3}{2} (0.4 * 2 - 0.2*1) * 103 J\)
= 900 J
\(\Delta Q = \Delta W + \Delta U\)
= 1200 J