ABSTRACT
In Chapter 1, we learned that the strong force holds the nucleus together. The strong force is energy, and energy is required to pull a nucleus apart (thank goodness!). The energy required to separate a nucleus into individual nucleons is the nuclear binding energy. Nuclear binding energy could also be defined as the amount of energy released by the reverse process, that is, when a nucleus is assembled from its individual nucleons. Energy doesn’t just suddenly appear. It must come from somewhere. In our theoretical construction of a nucleus from protons and neutrons, it comes from mass. You may have learned that mass is always conserved or that energy is always conserved. However, mass and energy can be converted one into the other; therefore, they are collectively conserved. If matter is destroyed, energy is created. Likewise, it is possible to create matter from energy. Sounds like Star Trek, but it’s true! The mathematical equation that relates matter and energy is very simple, and very well known:
E mc= 2
(3.1)
Energy is equal to mass times the square of the speed of light (2.998 × 108 m/s). When using Equation 3.1, the appropriate unit for mass is the kilogram (kg), which makes the energy unit the joule (J = kg ⋅ m2/s2). Nuclear scientists like to think on the atomic scale and prefer to use the unified atomic mass unit (u) as a unit of mass. How does that convert to energy?
