In a closed insulated container a liquid is stirred with a paddle to increase the temperature. Which of the following is true?
- E = W 0, q = 0
- E = W = q 0
- E = 0, W = q 0
- W = 0, E = q 0
Answer
(1) E = W 0, q = 0
Solution
The container is insulated (adiabatic), so no heat is exchanged ⇒ q = 0
∵ The paddle does work on the liquid ⇒ W 0 (positive, work done on the system)
First law: E = q + W
⇒ E = 0 + W = W 0 (the temperature rises, so internal energy increases)
Answer: (1)