熱力学は、熱と仕事の関係を扱う物理学の分野だ。
Netsurikigaku wa, netsu to shigoto no kankei o atsukau butsurigaku no bun'ya da.
Thermodynamics is a field of physics that deals with the relationship between heat and work.
この機械の効率は、熱力学の原理に基づいて計算された。
Kono kikai no kouritsu wa, netsurikigaku no genri ni motozuite keisan sareta.
The efficiency of this machine was calculated based on the principles of thermodynamics.