Total Marks | 5 |
Starting Date | Thursday, July 11, 2013 |
Closing Date | Friday, July 12, 2013 |
Status | Open |
Question/Description | “If I clean my room, it will become more ordered and I will be breaking the second law of thermodynamics. Give your comments on it, either you agree or disagree by giving solid reasons.” |
IDEA SOLUTION
No, it is not a violation. Because YOU cleaned the room (expended energy to create order). The room did not become ordered all by itself.
Diasagree. Because you deliver energy as work to the room.
Entropy balance for closed system,
Δs = Q/T + σ_gen, with entropy generation σ_gen ≥ 0 (as stated by the 2nd law)
From the case, one will neglected Q/T part, then
Δs = σ_gen, with Δs < 0
σ_gen < 0 (impossibe)
Let’s evaluate from the 1st law of thermodynamic, then to the 2nd law.
1. Energy balance for closed system, while deliver work to clean the room
Δu = Q – W, Q = 0 ( W = -W’, because work added to the system)
Δu = W’ > 0
After sometime, internal energy will release heat as its functon of temperature
2. Energy balance after the room is tidy,
Δu = Q – W, W = 0 and Δu < 0 as energy is being released to surrounding from closed system.
Δu = Q < 0
3. Entropy Balance for closed system,
Δs = Q/T + σ_gen, σ_gen>0
σ_gen = Δs – Q/T, (Q = -Q < 0 and Δs<0)
σ_gen = Q/T – Δs > 0
then, Q/T > Δs
Concluded that heat divided by temperatur(entropy as term of Q/T) as energy delivered by work higher than decrease of entropy. Hence the second law criteria is fulfilled.