In most situations, forces can be grouped into two categories: contact forces and field forces.  Contact forces occur as a result of direct physical contact between objects. Field forces, however, act without the necessity of physical contact between objects. They depend on the presence of a "field" in the region of space surrounding the body under consideration. You can think of a field as a property of space that is detectable by the forces it exerts. Scientists think there are only four...

Forces affect every moment of our life. Our bodies are held to the Earth by force, and they are held together by the forces of charged particles. When we open a door, walk down a street, lift a fork, or touch a baby's face, we are applying force. Our body's atoms are held together by electrical forces, and the core of an atom, called the nucleus, is held together by the strongest force known to us—nuclear force.
The study of motion is called kinematics, but kinematics only describes the way...

Consider water flowing from a nozzle to a turbine vane. As the water hits the turbine vane, it exerts a force that causes it to move along the flow of direction. Force is an impact that changes an object's motion, shape, or orientation. Forces can be caused by physical contact, such as a push or pull, or through non-contact interactions, such as magnetic or gravitational forces. Force is a vector quantity with both magnitude and direction, and is measured in newtons (N) in the SI unit system.

Non-conservative forces are dissipative forces such as friction or air resistance. These forces take energy away from a system as it progresses. Unlike conservative forces, non-conservative forces do not have potential energy associated with them. This is because the energy is lost to the system and cannot be turned into useful work later.
Also unlike their conservative counterparts, they are path-dependent; where the object starts and stops does matter. For example, a grinding wheel applies a...

When a body is in motion, it encounters resistance because the body interacts with its surroundings. This resistance is known as friction, a common yet complex force whose behavior is still not completely understood. Friction opposes relative motion between systems in contact, but also allows us to move. Friction arises in part due to the roughness of surfaces in contact. For one object to move along a surface, it must rise to where the peaks of the surface can skip along the bottom of the...

In the analysis of structural systems, it is common to encounter members subjected to various forces and couple moments. Simplifying these systems can make the analysis more manageable and easier to understand. One approach to achieve this simplification is by moving a force to a point O that does not lie on its line of action and adding a couple with a moment equal to the moment of the force about point O.
The principle of transmissibility plays a crucial role in this process. According to...