According to the Law of Conservation of
Energy, if Sally throws a watermelon with 100
joules of energy off the roof of a building,
how much energy should the watermelon
have as it hits the ground?
A. 200 joules
C. 100 joules
B. 150 joules
D. O Joules

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.