# Forces of Nature | Definition, Types & Meaning

Have you read the concepts of “FORCE” in schools and colleges and wondered what its deeper essence is? Is it just push and pull, gravity and electromagnetics or is it something more than those?
Indeed, this post will give us a deeper perspective of the term “FORCE” and its fundamental types in nature.

## Force Definition

Physics deals with causes and effects, including the decay of particles, the falling of apples to the rotation of planets, and the big bang. Force is a quantity that describes interactions between objects that may change the object’s shape, state of motion, or direction. In general, all the forces in nature can be roughly boiled down to two types, i.e., push or pull. It doesn’t matter whether it’s mechanical or chemical forces; it can easily be put in these two boxes of push and pull.

Let us say; that when you drop an egg, it gets velocity as it goes down, i.e., it is getting in a state of motion from rest under the influence of gravitational field (Pull). Now the same egg, when it comes in contact with the ground, will get broken under the influence of contact force offered by the ground (Push). Similarly, when two atoms get closer, the type of interaction and force is also either pushing away or pulling near each other (Pull and Push).

Force is an interaction that causes a change in an object’s state of motion. It is a vector quantity, meaning it has magnitude and directions and follows vector algebra. SI unit is Newton, and the CGS unit is Dyne.

## Force Unit and Formula

The force is a vector quantity, meaning it has both magnitude and direction. It is expressed as the product of mass (m) with the acceleration (a) of the body. Mathematically this becomes:

$$F = ma$$

where m is the mass, and a is the acceleration of the body. And it is expressed in Newton (N) or kg.m/s2.

Since acceleration (a) is nothing but the rate of change of velocity (v) with respect to time. The above expression fundamentally becomes the body’s rate of change of momentum (p). Mathematically this becomes:

$$F = \frac{mv}{t} = \frac{\partial p}{\partial t}$$

The unit of the force depends on the measurement system used. Broadly, there are two major systems: standard international (SI) and Centimeter Gram Second (CGS).

The unit of forces in these systems are:

• Newton (N): In a SI unit, it is expressed as Newton, which is kg.m/s2.
• Dyne (D): In the CGS unit system, it is expressed as dyne, which is g.cm/s2.

## Fundamental Force of Nature

Fundamentally, four types of forces govern the interaction of any physical system. Irrespective of what is doing to the bodies it can fit in any of these boxes of fundamental forces.

The fundamental forces of nature are:

• Gravitational force: The force that acts between masses. Any object with a mass greater than zero will experience a gravitational force when interacting with any object. Example – the falling of egg as described above. The obvious question arises, how are these forces generated? And to answer that, Newton considered gravity as the literal attraction between objects, whereas Einstein proposed that it is a consequence of the bending of space-time.
• Electromagnetic force: The forces that act between charged particles like negatively charged electrons and positively charged protons. Electromagnetic forces are a combination of electric forces (that arise from charge) and magnetic forces (that arise from the motion of charge). And the carriers of these forces are termed photons.
• Strong nuclear force: This force binds the fundamental particles together and acts within the nucleus. It acts on the quarks that make up the fundamental particle, i.e., proton and neutron. As the name suggests, it is the strongest of all forces, but its effects are only significant at small distances.
• Weak nuclear force: The force that arises during the decay of the particles. The carrier for these forces is considered to be bosons. And as the name suggests, it is the weakest of all forces and can only show effects at small distances.

To formulate a “Theory of Everything”, scientists are pursuing to unify these four forces that can define any physical system’s interaction. (That we will discuss in another post.)

This blog post shows that every force can be simplified into fundamental forces.

## Types of Forces

The basic behavior of force is either to push or pull. But does it always require contact between bodies to exert the force? No. As a result, we can classify the forces into two categories based on the nature of the contact.

Classification of forces based on the nature of contact:

• Contact forces: As the name suggests, these forces arise when two interacting bodies are considered to be in physical contact with each other. These forces include Tension forces (The force exerted by an object when pulled upon from an opposite end), Friction forces (The force that arises when one object moves or tends to move across another object), and Normal forces (It is an interesting concept, even though in many cases it’s equal to the weight of the object, but weight is a non-contact force, whereas Normal forces always arise because of contact).
• Non-contact forces: As the name suggests, these forces can arise even when the two interacting bodies are not in physical contact with each other and maintain a certain distance. However, they can generate push and pull between the objects. These forces include Gravitational forces (The force that arises due to the masses of objects), Electrical forces (The force that arises due to the charge on the body), and Magnetic forces ( The force that arises due to the magnetic behavior of the body).

## Conclusions

Force is everywhere, whether within the atoms of our body or galaxies. In one way or another, we are just a result of forces and interactions.

Some key learnings from this post:

• Force: It is a quantity that describes interactions between objects that may change the object’s shape, state of motion, or direction. It is a vector quantity with SI unit Newton.
• Fundamental forces: There are four fundamental forces – Gravitational forces, Electromagnetic forces, Strong nuclear forces, and Weak nuclear forces.
• Classification: Broadly, forces can be of two types – contact forces and non-contact forces

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