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%

with the invention of the automobile, the woman of the house could drive to the store and get groceries. women were also free to socialize more. during world war ii women were allowed to work in factories to the war effort and could drive to work or ride mass transit buses to their jobs.

conservation of mass

mass before something happens = mass afterwards