Three different processes act on a system. (a) In process A, 49 J of work are do

Question

Three different processes act on a system.
(a) In process A, 49 J of work are done on the system and 70 J of heat are added to the system. Find the change in the system's internal energy.
J
(b) In process B, the system does 49 J of work and 70 J of heat are added to the system. What is the change in the system's internal energy?
J
(c) In process C, the system's internal energy decreases by 126 J while the system performs 126 J of work on its surroundings. How much heat was added to the system?
J

Explanation / Answer

From the laws of thermodynamics we have

Heat energy given to the system = Work done by the system

                                                           + change in the internal energy of the system

Q = w + U

a) in the process A, Q = 70 J and w = -49 J

So the change in internal energy, u = Q - w = 70 + 49 = 119 J

b) Similarly,   u = Q - w = 70 - 49 = 21 J

c)  U = 126 J

     w = 126 J

heat added to system = Q = w + U = 126 + 126 = 252 J

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.