During compression of a spring the work done is 10 kJ and 2 kJ escaped to the surroundings as heat. The change in…
Thermodynamics · Class 11 · JEE Main Previous Year Question
During compression of a spring the work done is 10 kJ and 2 kJ escaped to the surroundings as heat. The change in internal energy, (kJ) is:
- a
−8
- b✓
8
- c
12
- d
−12
8
🧠 First Law: (IUPAC) — work done on spring stays in the system Work is done on the spring (system gains energy). Some of that energy escapes as heat (system loses energy). Net change = what stays.
🗺️ Calculation (work done on system — positive in IUPAC) (heat escaped from system — negative)
The system gained a net 8 kJ of internal energy.
⚠️ Trap: "Heat escaped" means for the system. Don't add +2 kJ — it left the system, so it's −2 kJ.
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