ABSTRACT
A major unifying concept is energy and how energy is transferred. The area that deals with heat, a form of energy, is called thermodynamics. Moving objects, doing work, and changing position between interacting particles requires energy, so energy and work are measured by the same units. Heat is another form of energy, thermal energy. Energy can be used to do work and to heat an object or space and be transformed to electrical energy or stored as potential energy. Efficiency in transportation is an example of the difficulty in formulating a rational energy policy that would convert the world to sustainable energy within the environmental limitations. Every US president since 1973 has called for energy independence, primarily due to the high cost of imported oil. The United States, with 4.5% of the population of the world, consumes 19% of its energy resources and a major portion of the mineral resources; demand from the developing world is increasing.
