Britannica Educational Publishing 
Energy [PDF ebook] 

While it cannot be seen, energy is all around us. Defined as the capacity to do work, energy can be transferred from one entity to another, and exists in many different forms. This detailed volume examines the basics of energy, both kinetic and potential. Forays into more complex concepts, such as nuclear fission and fusion, the relationship between energy and matter, and thermodynamics are discussed as well.