As shown in the figure, a system undergoes the process abc , absorbing 80 J of heat while performing 30 J of work. If the system performs 10 J of work during the process adc , calculate the amount of heat that flows into it during this process.

Step-by-step solution

According to the first law of thermodynamics: Q = U + W For the process abc , the heat absorbed is Q_ abc = 80 J and the work done is W_ abc = 30 J . The change in internal energy is: U = Q_ abc - W_ abc U = 80 - 30 = 50 J Since internal energy is a state function, the change in internal energy U depends only on the initial and final states. Thus, U is the same for both paths abc and adc . For the process adc , the work done is W_ adc = 10 J . The heat absorbed during this process is: Q_ adc = U + W_ adc Q_ adc = 5