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Physics is the scientific study of matter and energy and how they interact with each other.
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Heat transfer is the transport of energy due to a temperature difference between different amounts of matter.
Based off the foundation of conduction, convection and radiation, uses principles from thermodynamics and fluid dynamics. Heat transfer (or heat) is thermal energy in transit due to a spatial temperature difference. Whenever there exists a temperature difference in a medium or between media, heat transfer must occur.