The Swirling Twirling StirlingDrew StephensAward: Top 100
School: millennium high school Energy conversions are all around us, and the rotation of the Stirling engine in my photograph is no exception. The cycle starts with the internal thermal energy of the hot water in the red cup, which is radiated to the metal plate; this energy is then conducted to the air inside a cylinder. As the thermal energy of the air increases, it expands allowing it to do work on the piston and thus convert the thermal energy to linear kinetic energy. Meanwhile, a crankshaft attached to the golden wheel converts the energy to rotational kinetic energy, spinning the wheel. Thus, the thermal energy of the water is ultimately converted to rotational kinetic energy. Separately, a light-emitting diode connected to a chemical cell battery is attached to the wheel to illustrate its motion. The cell works by converting its chemical energy (NOT the kinetic energy of the engine) into electrical energy; this electron kinetic energy is transferred to the photons through electroluminescence in the LED. Finally, these photons, combined with those reflecting off the engine from a flash at the end to illuminate the details of apparatus, travel as both particles and waves through the camera optics, hitting the CMOS sensor over the long time that the camera shutter is open and converting their kinetic energy to electrical energy via the photoelectric effect, creating electrical signals. As the light is moving due to the engine's kinetic energy, the path of its motion can be seen in the final digital data. 
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