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?

To do work, this truck uses energy stored in chemical fuel and an electrical battery. how much total energy does this truck put out?

An engineer designs a roller coaster so that a car travels horizontally for 152 ft, then climbs 137 ft at an angle of 34.0° above the horizontal. it then moves 137 ft at an angle of 48.0° below the horizontal. if we take the initial horizontal motion of the car to be along the +x-axis, what is the car's displacement? (give the magnitude of your answer, in ft, to at least four significant figures and give the direction of your answer in degrees counterclockwise from the +x-axis.)

Suppose a comet has an orbital period of 309.1 years around the sun. what is it’s average distance from the sun?