What is the nature of mechanical force, what is force, and what is the nature of force

"Force" is defined as "is the interaction between objects", or "is the cause of changing the state of motion of matter".

The essence of force is the interaction between material entities in the process of direct contact with each other. This is true for both the force and the "force" in the phenomenon of gravitational force. There is no question of "force" between celestial bodies.

The steady state between the celestial bodies is maintained by the dynamic equilibrium achieved by "motion". The "gravitational force" between celestial bodies, calculated by Newton's gravitational formula, is a non-real "force". "Force" and "motion" are not the same thing.

They are mutually causal, not one-way causality. The reason that changes the speed of motion of matter is not just the force, the mass field can also be a cause that changes the speed of motion of matter.

The essence of force is the interaction between objects, and in classical Newtonian mechanics, force is the cause of changing the state of motion of objects.

The development of modern physics divides the forces in the universe into four types, namely, gravitational force, electromagnetic force, weak interaction force and strong interaction force.

Among them, gravitational force is the earliest we understand, from the rumor that Newton was hit on the head by an apple, human beings began to think about what allows us to stand on the earth, not float away, gravitational force is of course used to bind macroscopic objects. The understanding of electromagnetic forces has led us to the age of electrical appliances, from radios to computer networks, which are inseparable from electromagnetism, from generators to electric motors, electromagnetic forces are the most useful forces that humans can control.

The weak interaction and the strong interaction are both for microscopic particles, we ordinary people know less, the weak interaction will cause radioactivity, and the force that binds the nucleon when the strong interaction occurs. The interaction between these microscopic particles determines the energy, light, and heat of the stars in the universe. We humans can only do research through high-energy accelerators.

The grand theory of the universe can describe the separation process of these forces, the moment the universe is born, the gravitational force, the electromagnetic force and the strong and weak interaction are unified, and then the gravitational force separates first. In the baryon era, the strong and weak interaction separated, and eventually the weak interaction force was separated from the electromagnetic force. A great bull like Albert Einstein has been trying to unify these four forces in his later years, but for the sake of the times, he has not been able to do so.

In essence, force is an interaction between matter. The effect of force is manifested in the deformation of the object or the change of the state of motion. In terms of the actual effect of force, the concept of force can be further generalized as:

Force is what causes an object to deform or cause a change in the state of motion of an object. The materiality, vectorality, and reciprocity of force reflect the fundamental properties of force, and force is the action of an object on an object to emphasize the substance produced by the force.

What is the nature of gravity? How exactly did it come about?

The force is what changes the state of motion of the object, that is, what produces the acceleration.

The motion of an object does not require force to sustain it, and the motion of an object is determined by its own properties (inertia).

If it is not subjected to force, it will remain stationary when it is stationary, and it will maintain a uniform linear motion state when it is moving.

The force (f) referred to in physics is the interaction between objects. Interaction is when the motion of one object changes due to the presence of other objects. How do you quantitatively describe interactions?

We define the force acting on an object at a certain moment, and this interaction is proportional to the rate of change of the object's velocity at that moment, and also to the mass of the object. If a certain unit is selected to make the scale coefficient as one, it is the quantitative method of force defined by Newton, that is, f=mawhere m represents the inertial mass of the object and a represents acceleration.

This formula uses the International System of Units, the unit of mass is kilograms, and the unit of acceleration is meters per square second, so the unit of force in Si is kilogram meters per square second (kg·m·s-2), which is Newton (n).

Why is it defined that way? Because the principle that defines any concept is to be easy to use. We can examine the rationality of this definition from the most basic facts. These facts are: the uniformity and isotropy of space-time, the equality of arbitrary inertial frames, and so on.

Mechanical energy is the sum of kinetic energy and potential energy, and the potential energy here is divided into gravitational potential energy and elastic potential energy. We refer to kinetic energy, gravitational potential energy, and elastic potential energy collectively as mechanical energy. It is mass and velocity that determine kinetic energy; It is the mass and height that determine the gravitational potential energy; The elastic potential energy is determined by the stiffness coefficient and the deformation.

Mechanical energy is simply the sum of kinetic energy and potential energy. Mechanical energy is a physical quantity that represents the state of motion of an object. There is a conversion between the kinetic energy and the potential energy of an object.

In the process where only kinetic energy and potential energy are converted into each other, the total amount of mechanical energy remains the same, i.e., mechanical energy is conserved.

For example, if a car moving on the ground has only kinetic energy, and the potential energy is zero (with the ground as the reference plane), then the mechanical energy is equal to the kinetic energy; An airplane flying in the sky, that is, it has kinetic energy and gravitational potential energy, then the mechanical energy is kinetic energy and aggravating force potential energy; The kinetic energy of an object suspended by a spring is zero, there is gravitational potential energy and elastic potential energy, then the mechanical energy is gravitational potential energy plus elastic potential energy.

Mechanical energy is the sum of kinetic energy and potential energy, and here potential energy is divided into gravitational potential energy and elastic potential energy.

Mechanical energy means that only kinetic energy and potential energy are converted into each other, and the total amount of mechanical energy remains the same, that is, the increase or decrease of kinetic energy is equal to the decrease or increase of potential energy, which is the law of conservation of mechanical energy. Mechanical energy is related to the mechanical motion of the whole object. When friction is present, a part of the mechanical energy is converted into heat energy, which is lost in the air, while the other part is converted into kinetic or potential energy.

Therefore, if there is no conservation of mechanical energy in nature, then the perpetual motion machine proposed by Leonardo da Vinci cannot be manufactured, that is, there is no perpetual motion machine.

From the point of view of energy conversion, as long as the total amount of mechanical energy of the system remains constant in a certain physical process, and there is no conversion of mechanical energy into other forms of energy within the system or between the system and the outside world, and no other form of energy is converted into the mechanical energy of the system, then the mechanical energy of the system is conserved, and it has nothing to do with whether the mutual conversion of kinetic energy and potential energy must occur within the system.

For example, an object moving in a straight line at a uniform speed on a smooth horizontal plane.

The law of conservation of mechanical energy is formulated as follows: When only gravity does the work, the kinetic energy and potential energy of the object are converted into each other, but the total amount of mechanical energy remains the same. This is the most common case of the law of conservation of mechanical energy (i.e., in the mutual conversion of gravitational potential energy and kinetic energy, only gravity comes into play).

In fact, in the mutual conversion of gravitational potential energy with elastic potential energy and kinetic energy, when only gravity and spring elasticity do the work, the sum of the kinetic energy of the object and the potential energy of the system remains constant, and the mechanical energy of the system is conserved), which is also a special case of the more general law of conservation of mass.

Mechanical stress refers to the internal force that produces interaction between various parts of the object when the object is deformed due to external factors (force, humidity changes, etc.), so as to resist the action of such external factors, and try to restore the object from the deformed position to the position before the deformation. The common stress phenomenon is that the steel wire is not easy to straighten and rewind.