Kindling Students' Interest in Virtual Work Method: Advantages and Challenges

In mechanics, work is energy in transition to a body due to force or moment acting on the body through a displacement. Like heat, work is a scalar quantity occurring during a process. A virtual work is the work done by a force or moment due to a virtual displacement of the body. By giving a compatible virtual displacement for the system and applying the principle of virtual work, we can solve many complex as well as simple problems in mechanics without a need to solve coupled simultaneous equations. This powerful feature of the virtual work method may initially appear as a magic black box to students, but it kindles great interest and excitement in them. This paper reviews the fundamentals of the virtual work method, compares it with the conventional method, and points out the inherent advantages and challenges. Seemingly challenging examples in addition to simple examples are included. I. Fundamental Concepts Engineering and technology students learn the definition of work when they take the course in physics usually in their freshman year. In mechanics, a body receives work from a force or a moment that acts on it if it undergoes a displacement in the direction of the force or moment, respectively, during the action. It is the force or moment, rather than the body, which does work. Before reaping advantages in the virtual work method, it is well to refresh certain fundamental concepts, which sometimes appear as challenges to beginning students. Work of a force. The work U 12 → done by a force F on a body moving from position A1 along a path C to position A2 is defined by a line integral. It is given by 1-4