2.4 : Force Classification

Forces play a crucial role in the study of physics and engineering. They are essential in describing the motion, behavior, and equilibrium of objects in the physical world. Forces can be classified based on their origin, type, and direction of action.

Contact and non-contact forces are two of the most widely used categories of forces. As the name suggests, contact forces require physical contact between two objects to act upon each other. Examples of contact forces include frictional, tensional, and normal forces that arise due to surface contact. On the other hand, non-contact forces can act on an object without any physical contact between the object and the source. Examples of non-contact forces include gravitational forces between celestial bodies, magnetic forces between two magnets, and electrostatic forces that cause attraction or repulsion between charged particles.

Another way to classify forces is based on their distribution. A concentrated force is a force that acts at a specific point on an object. An example of a concentrated force is a hammer hitting a nail. When the hammer strikes the nail, it exerts a concentrated force at the point of contact between the hammer and the nail. Conversely, distributed forces act over the entire surface area or volume of an object. These forces can be further classified as uniform or non-uniform, depending on whether the force is the same at all points of the object. Examples of distributed forces include the force exerted by a uniform fluid acting on the surface of a body, air resistance acting on vehicles moving through the air, and the force exerted by a person's hand on a table. Force classification is an important concept in mechanical engineering because it enables engineers to understand and predict the behavior of structures and machines under various loads.