Fundamentals of Physics

In a procedure commonly used in childbirth, a surgeon or an anesthetist must run a needle through the skin on the patient’s back, then through various tissue layers and into a narrow region called the epidural space that lies within the spinal canal surrounding the spinal cord. The needle is intended to deliver an anesthetic fluid. This tricky procedure requires much practice so that the doctor knows when the needle has reached the epidural space and not overshot it, a mistake that could result in serious complications. So far, that practice has been with actual patients. In the near future, however, new doctors might be able to practice on virtual-reality simulations before injecting their first patient.

How should that simulation be programmed in order to give a practicing doctor the proper feel of an epidural procedure?

The answer is in this chapter.

7-1 What Is Physics?

One of the fundamental goals of physics is to investigate something that everyone talks about: energy. The topic is obviously important. Indeed, our civilization is based on acquiring and effectively using energy.

For example, everyone knows that any type of motion requires energy: Flying across the Pacific Ocean requires it. Lifting material to the top floor of an office building or to an orbiting space station ...