Which one of these are considered as mechanical energy? Chemical energy
Nuclear energy
Thermal energy
Radiant energy
Electrical energy
gravitational potential energy
rotational kinetic energy
translational kinetic energy
elastic potential energy

Full change in the electric plus system

If the heat engine is a perfect carnot cycle engine, thenefficiency = (t2-t1)/t2   where t1=temperature of cold reservoir ( ° k) = 135            t2=temperature of hot reservoir ( ° k)   = 325thereforeefficiency = (t2-t1)/t2 = (325-135)/325 = 0.5846 = 58%  note: this is the theoretical maximum efficiency of a perfect heat engine.   real-life engines do not achieve this value.