An air parcel undergoes compression (i.e., its volume decreases), then its internal energy ____ [Given: First law of thermodynamics dU = dQ + dW, where dW = -PdV, and dQ = 0]

Correct option is C

· According to the First Law of Thermodynamics:
dU=dQ+dW
where:
· dU is the change in internal energy,
· dQ is the heat exchange, and
· dW is the work done by the system.
· In this scenario:
· The process involves compression, so the volume decreases (dV<0 ).
· The work done on the system (dW=−PdV) is positive.
· Since dQ=0 (no heat exchange), the change in internal energy dU is entirely due to work done on the system:
dU=dW=−(−PdV)=PdV which is positive.
· Therefore, the internal energy increases during compression.
Additional Knowledge: 1. First Law of Thermodynamics:
· dU=dQ+dW: Energy conservation principle applied to thermodynamic systems.
· Heat added to a system and work done on the system both contribute to changes in internal energy.
2. Work during compression/expansion:
· Compression (dV<0): Work is done on the system, increasing internal energy.
· Expansion (dV>0): Work is done by the system, decreasing internal energy.
3. Adiabatic Compression:
· If no heat is exchanged (dQ=0), as in this case, the process is adiabatic.
· During adiabatic compression, the temperature and internal energy of the gas increase.
4. Real-life applications of compression:
· Compression is used in heat engines, refrigerators, and air compressors, where changes in internal energy are crucial for their operation.
5. Practical considerations:
· In real gases, deviations from ideal behavior might slightly modify these results, but the increase in internal energy due to compression generally holds