🔥 Thermodynamics – Stage 3

Page 5 : Extreme Traps & One-Line Killer Logic

This page focuses on questions that look simple but destroy rank if logic is weak.

Trap 1️⃣ : Heat Supplied ≠ Temperature Increase

A gas absorbs heat but temperature remains constant.

Killer Logic:
ΔT = 0 ⇒ ΔU = 0 ⇒ Q = W

❌ Heat supplied does NOT always raise temperature

Trap 2️⃣ : Zero Work ≠ Zero Heat

Isochoric process (volume constant).

W = 0 but Q = ΔU

❌ Students wrongly mark Q = 0

Trap 3️⃣ : PV Diagram Direction

Clockwise cycle on PV graph.

Clockwise ⇒ Gas does positive work

❌ Shape doesn’t matter, direction matters

Trap 4️⃣ : Same Temperature ≠ Same Internal Energy

Monoatomic and diatomic gases at same T.

U ∝ (Degrees of freedom) × T

❌ Temperature alone does not fix U

Trap 5️⃣ : Free Expansion Confusion

Gas expands into vacuum.

Q = 0, W = 0 ⇒ ΔU = 0 ⇒ ΔT = 0

❌ Volume change ≠ temperature change

Trap 6️⃣ : Efficiency vs COP

Refrigerator & heat engine comparison.

Efficiency < 1
COP can be > 1

❌ Applying efficiency formula to refrigerator

Trap 7️⃣ : Entropy Zero Myth

Isothermal reversible process.

ΔS = Q_rev/T ≠ 0

❌ Constant temperature ≠ constant entropy

Trap 8️⃣ : State vs Path Confusion

Work depends on path, internal energy does not.

U → state function
W, Q → path functions

Trap 9️⃣ : Graph Interpretation Kill Shot

Area under PV curve = Work
Slope of P-V curve ≠ Work

Trap 🔟 : Final State Equals Initial State

ΔU = 0
But Q and W may NOT be zero

✅ Stage 3 – Page 5 Completed
➡️ Next: Stage 3 – Page 6 (Multi-Concept PYQs with Hidden Traps)

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🔥 Thermodynamics – Objective Final Revision

Thermodynamics – Set 1
Set 2
Set 3
Set 4
Set 5
Set 6
Set 7
Set 8
Set 9
Set 10
Set 11
Set 12
Set 13
Set 14
Set 15
Set 16
Set 17
Set 18
Set 19
Set 20
Set 21
Set 22
Set 23
Set 24
Set 25
Set 26
Set 27
Set 28
Set 29
Set 30
Set 31
Set 32
Set 33
Set 34
Set 35
Set 36
Set 37
Set 38
Set 39
Set 40
Set 41
Set 42
Set 43
Set 44
Set 45
Set 46
Set 47
Set 48
Set 49
Set 50
Set 51
Set 52
Set 53
Set 54
Set 55
Set 56
Set 57
Set 59

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