Application of Newton's Laws
Knowledge of the forces required to maintain an object in equilibrium is essential in
understanding the nature of bodies at rest and in motion.
STATE the conditions necessary for a body to
be in force equilibrium.
DEFINE the following:
When forces act on an object, the result may be a change in the object's state of motion. If
certain conditions are satisfied, however, the forces may combine to maintain a state of
equilibrium or balance.
To determine if a body is in equilibrium, the overall effect of all the forces acting on it must be
assessed. All the forces that act on an object result in essentially one force that influences the
object's motion. The force which results from all the forces acting on a body is defined as the
net force. It is important to remember that forces are vector quantities. When analyzing
various forces you must account for both the magnitude (displacement) of the force as well as
the direction in which the force is applied. As described in the previous chapter, this is best
done using a free-body diagram.
To understand this more clearly, consider the book resting on the table in section A of