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Let 100J of work is done to compress a gas adiabatically, then change in internal energy is:

Correct answer: A. 100J

  • A. 100J
  • B. +50J
  • C. -100J
  • D. -50J

Explanation

In an adiabatic process, there is no exchange of heat with the surroundings (Q = 0). According to the first law of thermodynamics, the change in internal energy (ΔU) is equal to the work done on the system (W) minus the heat exchanged (Q). Therefore, ΔU = W. Since 100J of work is done to compress the gas, the change in internal energy is +100J. The other options incorrectly interpret the conversion of work into internal energy in an adiabatic process.

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About First Law of Thermodynamics

The first law relates heat supplied, work done and the change in internal energy through energy conservation. Problems use sign conventions and apply the law to isothermal, adiabatic, isobaric and isochoric processes. Internal energy is a state function, while heat and work depend on the path followed.

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