In a way, static equilibrium can be thought of as a study of nothing happening.  As we’ll find out, systems that are in static equilibrium are not really exciting systems to watch.  Nevertheless, the study of systems in static equilibrium is an extremely important subject.  (Engineering students take an entire course called “Statics” which studies nothing but this subject!) 

An important aspect of static equilibrium is the study of the conditions under which systems will remain in static equilibrium.  Systems such as buildings, bridges, balconies, archways, etc., all have one thing in common: they are boring to watch because nothing much is going on with them, and we would really prefer that it would stay that way (you don’t want the structure of a bridge to change just because you start driving across it!).

In this lecture we will study the conditions under which a system or object is said to be in static equilibrium.