• Saturday June 25,2022


We explain what friction or friction force is and what are its causes. In addition, static friction and kinetic or dynamic friction.

Friction is the force between two surfaces and is greater on rough surfaces.
  1. What is friction?

Friction, friction force or friction force is a force between two surfaces that are in contact, and that opposes the movement, that is, has a direction opposite to the movement . This force can be of two types: aesthetic (when opposed to the start of a slide) or dynamic (when opposed to relative motion).

The frictional force is not one of the fundamental forces of the universe, as is gravity, but it is due to the complex interaction between the surface of two objects in physical contact. Friction is generally referred to for solid objects, but there is also friction in liquids: the effect of friction between the layers of a liquid substance Define its viscosity.

To set an object at rest in motion, the force that pushes it to move must precisely overcome the resistance exerted by friction, which is greater between rough and irregular surfaces than on smooth and polished surfaces .

Likewise, an object that is in motion without a constant force on its side will see its speed diminished as the friction force overcomes that of the initial thrust. On the other hand, heavier objects show greater friction than light objects, in cases where gravity adds to the resistance to movement.

Friction, in addition, can cause impact on the moving surface. It is noticeable because it often generates heat, or even wear on both surfaces .

It can serve you: Mechanics in physics

  1. Causes of friction

Even the air causes friction on objects moving at high speeds.

The friction may be due, first of all, to micro-imperfections between the two surfaces in contact, which make it difficult to slip from one to the other, even if in appearance they cannot be perceived. This is the reason that some surfaces have more friction than others.

On the other hand, friction can be reduced mechanically, by adding lubricants, for example. If you want to increase friction, the surfaces can be dried. However, it also occurs between particles due to the electromagnetic attraction between them, which is explained by one of the fundamental laws of matter.

  1. Static friction

The first of the types is static friction (F e ): it tends to oppose the relative displacement between two surfaces in contact. It is the force necessary to overcome to start the movement of an object. It is always less than or equal to the coefficient of friction between the two surfaces multiplied by the normal force.

This static friction is usually greater than the dynamic one, which explains why it is more difficult to start pushing a heavy piece of furniture on rough ground, than to keep pushing it once it is already in motion.

  1. Kinetic or dynamic friction

Dynamic friction (F d ) is the force that opposes the displacement of an object that is already in motion, as opposed to static friction.

It is a constant magnitude, since the amount of force necessary to keep the movement moving is the same (as long as it is not interrupted for some reason). Therefore, it is equal to the coefficient of dynamic friction, denoted by the Greek letter μ .

The differences between static and dynamic friction are not entirely understood at the physical level, but it is known that the prolonged action of static is more difficult to overcome, as is the case with things that have been in the same place for too long, due to attractions and microsoldaduras between the surfaces.

  1. Examples of friction

Friction prevents rocks from sinking rapidly in water.

The examples of friction are innumerable. Friction is that force that opposes us moving an old piece of furniture by pushing it with our forces. It is also the force that will stop and jump a flat stone that we throw sideways on the surface of the water.

The friction force is what the brakes use to hold a car in place when we park it on a steep hill, and it is the same as, if we brake suddenly driving the same car at high speeds, reduce the speed and displacement of the car overcoming inertia.

Other common examples of friction have to do with the heat generated by friction, such as when we light a fire by rubbing two wooden sticks against each other, or when we suffer a burn from rubbing a rope in sudden movement when we were holding it in our hands.

Follow with: Newton's Laws

Interesting Articles



We explain to you what coexistence is, the question of whether the human being is selfish or solidary by nature and the patterns of coexistence. Coexistence is the relationship of people with the social groups that they integrate. What is living together? Coexistence is the physical and peaceful coexistence between individuals or groups that must share a space



We explain what mortality is, what is the mortality rate and what is birth. In addition, infant morbidity and mortality. It is known that human mortality is higher in men than in women. What is mortality? Human beings are mortal, that is, we are going to die, and therefore we have a particular relationship with mortality



We explain what indifference is and what are its possible causes. In addition, some examples of this feeling. Indifference can indicate an attitude of survival, such as a shield or armor. What is indifference? Indifference is that feeling of remaining immobile , both in motion and in feeling, in the face of any situation, idea or person



We explain to you what the geosphere is and how its structure is. In addition, how this set of layers is composed and its importance. The study of the geosphere is carried out through the experimental review of the soils. What s the ge sphere? In the natural sciences, the set of layers that make up the solid part of the Earth is called the `` sphere '' or `` geosphere

Philosophical Disciplines

Philosophical Disciplines

We explain to you what they are and what are the philosophical disciplines, what they are dealing with and the characteristics of each one. Philosophical disciplines offer different views on human existence. What are the philosophical disciplines? Philosophical disciplines, also called branches of philosophy, are the various aspects of study that comprise philosophy , that is, that are inserted into it as a much larger field

Effective Communication

Effective Communication

We explain to you what effective communication is and what its elements are. In addition, why it is so important and some examples. It is very important that the issuer knows clearly what he wants to transmit. What is effective communication? Effective communication is one in which the sender and the receiver encode a message in equivalent form