A mechanical engineer might be concerned about how much power is required to supply water through a piping system in a building. He or she might also be concerned with the aerodynamic drag of an automobile. The flow of energy due to a temperature difference is called heat transfer, another thermal science area in which mechanical engineers are involved. They predict and study the temperature of components in environments of operation. Modern personal computers have microprocessors that require cooling.
Mechanical engineers design the cooling devices to allow the electronics to function properly.
Mechanical engineers design and develop engines. An engine is a device that produces mechanical work. Examples include internal combustion engines used in automobiles and gas turbine engines used in airplanes. Mechanical engineers are involved in the design of the mechanical components of the engines as well as the overall cycles and efficiencies of these devices. Performance and efficiency are also concerns for mechanical engineers involved in the production of power in larger power generation systems.