A simple heat engine might make use of the warm air around New York city. Enegy could be takenn as heat from the atompsphere (assume 30 celcius) and rejected as heat to the Hudson River (10 celcius). What is the maxmum effeciency of such an engine for the conversion of thermal enegy into mechanical energy?

66.7%

Explanation: The efficiency of an ideal heat engine is given as

E = 1 - Tc/Th

Where E = efficiency, Tc = temperature at cold region = 10°c and Th = temperature at hot region = 30°c

E = 1 - 10/30

E = 1 - 1/3

E = 1 - 0.333

E = 0.6667 or 66.7%

potential energy is directly proportional to height.

more height = more potential energy.

greatest increase in height = greatest increase in potential energy

where are the points with the greatest increase in height ?

has to be c-e or d-e .