Asked in PMC Practice Test 7 (2021) 2021Moderate

If 110J heat is added to the system and 40J work is done, then the change in internal energy system should be:

Correct answer: A. 70J

  • A. 70J
  • B. 150J
  • C. 190J
  • D. 180J

Explanation

Since heat is being added, so work is being done by system. ΔU = Heat supplied - Work done by the system= 110 - 40 = 70J

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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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