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?

Identify the correct relation showing that the radius r of the orbit of a moon of a given planet can be determined from the radius r of the planet, the acceleration of gravity at the surface of the planet, and the time τ required by the moon to complete one full revolution about the planet. determine the acceleration of gravity at the surface of the planet jupiter knowing that r = 71 492 km and that t= 3.551 days and r= 670.9 × 10^3 km for its moon europa.