WHAT IS FORCE ?

A FORCE can be defined as "A push or a pull on an object". The FORCE (push or pull) may result from a contact between two objects, or from an influence in which no contact takes place, such as magnetism or gravitation. A FORCE can cause a change in motion of the object. If the object is not acted upon by other pushes and / or pulls which combine to form an equal and opposite counteracting action, then the FORCE will change the motion of the object to which it is applied.

Force is a vector quantity, meaning that it has both magnitude and direction. Forces are sometimes described in terms of magnitude only, and in many of those cases, the direction is self-evident.

Sir Isaac Newton, the 17th century English mathematician, formulated a series of observations about the basic behavior of forces on objects. Those observations have become known as "Newton's Laws of Motion", and are fundamental to the study of forces acting on objects. They are:

1. Every object continues in a state of rest or of uniform motion until it is compelled by a force to change its state of rest or motion.
2. The change in motion of an object is proportional to the net magnitude of the combination of the applied forces, and takes place along the straight line in which the ombination of the applied forces acts (sometimes stated as: F = MA, or  force = mass x acceleration).
3. For every action, there is an equal and opposite reaction. In other words, when two objects exert forces on each other, the forces are equal in magnitude, opposite in direction, and collinear.

The equation "F = MA" is a simplification of Newton's second law, but it has extreme significance. It means that the force required to accelerate an object is equal to the mass of the object multiplied by the desired acceleration. This simple equation forms the basis for determining the loads applied to objects as the result of motion ("dynamics").

Another common example of Newton's second law is the calculation of the force required to lift an object (its weight) The weight of an object is the acceleration of gravity (32.2 ft-per-second-per-second average on earth; quite different on other planets) times the mass of the object.