Concepts Of Physics MCQ Edition [Volume 2]PhysicsLaws of Thermodynamics
During a particular process, both the pressure p and the volume V of an ideal gas increase.
Options
- AThe temperature of the system must increase
- BThe heat supplied to the gas equals the change in its internal energy
- CThe work done by the system is positive
- DSuch a process is impossible
Correct answer
C. The work done by the system is positive
Step-by-step solution
For an ideal gas, the equation of state is pV = nRT . Since both pressure p and volume V increase, their product pV increases. Therefore, the temperature T of the gas must increase. The work done by the gas is given by W = p dV . Since the volume of the gas increases, dV > 0 , which implies that the work done by the system is positive. According to the first law of thermodynamics, Q = U + W . Since W > 0 , the heat supplied Q is greater than the change in internal energy U . Such a process is physically possible, f