ABSTRACT
As has been established in the previous chapters, Newton’s second law is an effective tool for analyzing the dynamics of moving objects. However, to apply Newton’s laws to a moving object, all forces acting on the object have to be specified in magnitude and in direction. In many cases, an alternative approach based on energy considerations can be followed. The energy-based approach is effective and very helpful because much of the formalism is cast in terms of scalars, not vectors. This approach starts with a definition of work done on the object by a force or forces acting on it. In addition to the kinetic energy that a moving object has, another energy concept, called potential energy, is introduced. This concept is linked to the work done on the object by a special kind of forces, called conservative forces, among which gravitational forces are a good example. Another quantity, called the total mechanical energy, which is defined as the sum of an object’s kinetic and potential energies, is also introduced and discussed in a variety of examples.
