ABSTRACT
Everything that happens in the universe entails energy. There are various forms of stored energy, namely, the energy of motion (kinetic energy), energy due to electromagnetic forces, energy due to gravitation (gravitational energy), and energy associated with nuclear forces. Energy release is associated with chemical bonds when the product compounds in a chemical reaction have lower total energy. Invisible energy is ubiquitous in the universe. It enables plants to grow and animals to live. Gaining an understanding of energy stored within matter is a fundamental goal of this book. The invisible energy stored within a liquid like water comes to life, at least in part, through what is called Brownian motion. A property shared by both a point particle and a rigid body is that neither can store energy internally. For a point particle, this is true because it occupies zero volume and there is nothing internal about it.
