Engine Efficiencies

—> when 2 systems interact and the 2 systems are a different temperature, heat energy will be exchanged between them

—> in an engine, heat is used to do work in objects (provide a force through some distance)
—> the hot gas left over is expelled

TH : temperature of heat source
TL : temperature of cold sink

Carnot Efficiency :

nMAX = 1 - TL/TH