# What is strength?

Regarding what force is, it is known that this intuitive concept has two important characteristics: it is a vector-like quantity and causes acceleration on bodies.

There is no exact definition for the concept of force, as the understanding of this magnitude is intuitive. In a simple way, we can understand what generates the action of forces on objects and what are the types of forces.

Force is a vector-type quantity , that is, it is defined from the numerical value (module), direction and direction information . The idea of force is associated with actions such as pulling, pushing, dragging, breaking, etc.

**types of strength**

Forces can be classified into two types:

When there is direct contact between two bodies. When pushing a car, for example, the force involved is of the contact type.**Contact forces:**When the force acts at a distance. The gravitational force between the Earth and the Moon and the electrical interaction force between two protons , for example, are forces that act at a distance.**Field Forces:**

**strength and movement**

When a force acts on a certain object, it will cause acceleration , that is, the object’s velocity will change during the time the force acts. **Therefore, we can conclude that when an object performs uniform rectilinear motion, type of motion with constant velocity, there are no forces acting on it, because if there is no change in velocity (acceleration), there is no resultant force.**

**strength and balance**

One of the necessary conditions for a body to be in equilibrium is that the sum of the forces acting on it is zero. There are two cases of equilibrium:

When the sum of the forces acting on an object at rest is equal to zero.**Static equilibrium:**When the sum of the forces acting on an object moving with constant velocity corresponds to zero.**Dynamic equilibrium:**

**Unit of measure for force**

According to Newton’s second law , **the resultant force acting on any object is given by the product of the mass and the object’s acceleration** . In this way, we have:

**F _{R} = m . The**

In the International System of Units (SI) , the units of measurement for mass (m) and acceleration are, respectively, **kg** and **m/s **^{2} . Therefore, the unit of measure for force will be the product of the units of mass and acceleration, or **kgm/s **^{2} . This unit is called the newton ( **N** ) in honor of Isaac Newton , so we have:

**1 kgm/s ^{2} = 1 N**