Types of Forces : 9 Important Facts You Should Know

The different kinds of forces depend on whether they result from contact or non-contact between two interacting objects. There are at least ten different types of forces that exist in the universe are listed below:

Applied Force
Normal Force
Frictional Force
Air Resistance Force
Tension Force
Spring Force
Gravitational Force
Electrostatic Force
Electromagnetic Force
Nuclear Force

The various types of forces are energies or strengths acting upon two interacting objects. We’ll discuss each of these forces we experience around us.

Read the article about Units of the Force and its correlation with the Work and Energy.

Types of Contact Force

Contact force is one of the major types of forces that acts when two interacting objects are in physical contact. Out of ten forces, the following six forces are classified as types of contact forces:

Applied Force
Normal Force
Frictional Force
Air Resistance Force
Tension Force
Spring Force

Explain the Types of Contact Force with Example

Applied Force

When a contact force is applied on the object by another object, it is known as “Applied Force”.
When force is applied to the object by the action of a person’s muscles, then the applied force is known as “Muscular Force”.
It is denoted as “F_app”.

For example, the applied force is the contact force exerted on the chair when someone pushes or pulls it across the room.

Normal Force

When a contact force is exerted upon any object in contact with another stationary object, it is known as “Normal Force”.
It is an opposing force denoted as “F_N”.
A normal force is applied perpendicularly to both the two interacting bodies which are in contact.

For example, when a book lying on the table, the normal force F_N acting on the book is given by,

$F_{N}= m \\ast g$

Where g = acceleration due to gravity or force of gravity, and m = mass of the book.

Note- There is no external force act on the book.

Now, if a book falling at an angle of θ, then the F_N is given by,

$F_{N}= m \\ast g + Fsin\\theta$

Where $Fsin\\theta$ is an external force.

In both cases, the force of gravity ‘g’ pulls the book towards the earth. But the normal force F_N tries to prevent the book from its descent toward the ground.

Hence, the normal force counters or opposes the force of gravity, which is why it is known as “Opposing Force”.

Frictional Force

When the object’s surface exerts a contact force on another object as it moves across the surface or makes an effort to move across it, it is known as “Frictional Force”.
It is an opposing force denoted as “F_frict”

For example, if a man skating across the ice surface, the surface of ice exerts a frictional force opposite its motion.

Friction Force — **Frictional Force Example** (Image Credit: Performance Simulation)

The frictional force on a man by ice surface can be calculated using the formula,

$F_{fric} = \\mu \\ast F_{N}$

F_N is the “Normal Force,” and μ is called “Coefficient of Friction” which depends on the object and the specific situation.

Types of Frictional Force

The types of frictional forces are categorized based on types of motion as:

Static Friction: This frictional force acts between the surfaces when they are at rest concerning each other. E.g., A stationary ball on the field
Sliding Friction: This frictional force acts between the surfaces when they are slipping or sliding against each other. E.g., Opening any window.
Rolling Friction: This frictional force between the surfaces opposes the motion of an especially circular-shaped object. E.g., The wheels of any vehicle.
Fluid Friction: This frictional force acts upon an object by the fluid layers when moving relative to each other. E.g., Swimming in the pool.

Air Resistance Force

When a contact force is exerted on any object as it progresses through the air, it is known as the “Air Resistance Force”.
It is an opposing force denoted as “F_air“
Since it is resistive, the force of air resistance is often opposing the movement of an object.
Because of its negligible magnitude and mathematically tricky to predict its value, the air resistance force is frequently neglected.

For example, when a skydiver parachuting from an airplane towards the ground, there is some resistance the skydiver experiences against the air called air resistance.

Air Resistance Forces — **Air Resistance Force** (Image Credit: Wikieducator)

Hence, the equation of Air Resistance Force F_air that tries to decrease the velocity(v) of a skydiver who was falling downward is given as:

$F_{air} = c \\ast v ^ {2}$

Where c is air constant.

Tension Force

When a contact force is exerted on the body when hung from objects, it is known as “Tension Force”.
It is a pulling force denoted as “F_T”

For example, the seat belt clip must withstand the force of a body being propelled forward during a traffic accident.

How to calculate Tension Force?

The tension force acting on any object can be calculated using Tension Formula.

Tension Formulas

Since tension is acting on the body while in a hanging state, then its formula will be:

$T = F_{N} \\pm ma$

Where ‘F_N’is the normal force acting on the body = mg,

If the body is accelerated upward, the tension on the body will be $T = mg + ma$
If the body is accelerated downward, the tension on the body will be $T = mg - ma$
If the tension on the body is equivalent to the weight of body $T = mg$

Spring Force

When a contact force is exerted on any object by attached compressed or stretched spring, it is known as the “Spring Force”.
When an object compresses or stretches a spring, it is always acted by a contact force that restores objects to their equilibrium position.
It is a restoring force denoted by “F_s”.
The spring force on an object is directly proportional to the amount of compression or stretch of the spring by an object.

For example, in Simple Harmonic Motion(SHM), the spring force (F_s) and the displacement (x) of an object always have opposite signs.

A constant of proportionality (k) makes it reasonable to construct the equation for the spring force as follows,

$F_{s} = - k \\ast x$

The equation is called as Hooke’s Law for springs, where k is the spring constant.

Types of Non-Contact Forces

Non-Contact force is one of the major types of forces that acts when two interacting objects are not in physical contact. Out of ten forces, the following four forces are classified as types of non-contact forces:

Gravitational Force
Electrostatic Force
Electromagnetic Force
Nuclear Force

Explain the Types of Non-Contact Force with Example

Gravitational Force

This idea of gravity or gravitational force was first introduced by Sir Issac Newton.
He defined gravity as ‘a natural attraction between any two interacting objects’.
The gravity on any object upon earth is directed downward direction towards the earth’s centre. It is always equal to the object’s weight. i.e.

$F = m \\ast g$

Here the g is a physical constant and g = -9.8 m/s2 (on Earth).

When an object encounters no other forces than the force of gravity, the object’s acceleration appears to be equal to the constant ‘g’. Hence, the contact ‘g’ is also called “Acceleration due to gravity“. However, the constant ‘g’ is also present despite the object’s acceleration when other forces act on it.

Gravitational Force between two objects

The gravitational force or the force of gravity between two interacting objects can be determined using Newton’s universal law of gravitation.

Gravitational Force Formula

“The force of attraction (F) between any two interacting objects is directly proportional to the product of their masses (m₁,m₂), and inversely proportional to the square of the distance(r) between them.”

Gravitational Force Formula is given by,

F ∝ $(m_{1} \\ast m_{2}) / r^{2}$

Where,

F = G $(m_{1} \\ast m_{2}) / r^{2}$

Where G is Gravitational Constant

This equation is also known as the Gravitational Force between two interacting objects.

Electrostatic Force

Similar to gravitational force, a force acts between two bodies when they are charged, known as “Electrostatic Force”.
Since all bodies are made up of different positive, negative, and neutral particles.
Depending on the charge of bodies, the Electrostatic force between bodies can be both attractive and repulsive.

For example, when you rubbed any glass rod with cloth, the rubbing tends to develop a certain charge on the glass rod.

Electrostatic Force Formula

The electrostatic force between two charged bodies having charges (q1,q2) and separated by distance(r) is given by,

F = k_e $(q_{1} \\ast q_{2}) / r^{2}$

Where k_e is the Coulomb’s constant and equal to 8.988×109 N⋅m²⋅C−_²) .

Electromagnetic Force

When the force of attraction or repulsion between charged particles involves electric and magnetic interactions, it is known as “Electromagnetic Force”.
This force is carried between charged particles through the photons, a particle component of light energy.
This force is capable of the binding of atoms and hence, for the structure of solid objects. Consequently, Electromagnetism decides all electrical and chemical processes.
This force is also responsible for the contact force, such as normal force and friction.

Electric Force

The electric force occurs on charged particles due to their attraction or repulsion with each other.
For example, electrons are held together by the nucleus.
This force is not based on the particle’s mass but depends on the particle’s “electric charge“. Therefore, the electric force between electrons is equal to the electric force between protons when placed at an equal distance.

Magnetic Force

The magnetic force occurs on the”magnetic poles” of magnetic objects due to their attraction or repulsion with each other.
Moving charges on magnetic objects that have north and south poles create magnetic force between electrically charged particles, either a pull (attraction) force or push (repulsion) force.

Relationship between Electricity and Magnetism

When an electromagnetic force acts on charged particles, flowing electrons produce magnetism, and moving magnets produce electricity.
A field between charged particles is created when electric components of force act between moving or stationary charged particles.
Once the particles set into motion, they began to show the magnetic component and created a magnetic field around them.

For example, when electrons pass through the wire to turn on any home appliances, the wire becomes magnetic.

Hence, the electromagnetic force between charged particles produced two related phenomena, electricity and magnetism. Together, both form “Electromagnetism”. Scottish physicist James Clerk Maxwell explains this relationship between electricity and magnetism.

Nuclear Force

Nucleus force is a binding force that binds all the charged particles together within and around the nucleus. Depending upon the strength of the force, Nuclear Force is further classified into two types of forces:

Strong Nuclear Force

The strong nuclear force is the strongest among non-contact forces because of the strong atomic interaction between particles.
This strongest force is responsible for binding the particles of matter unitedly to form more massive particles.
However, its range is small. It operates when particles are incredibly close to one another.

Weak Nuclear Force

The weak nuclear force is the weak among non-contact forces because of weak nuclear interaction between particles. This weak interaction is further responsible for particle decay.
During nuclear decay, this weak nuclear force makes proton particles convert into neutron particles and vice versa.
It is stronger than the force of gravity but only acts at infinitesimally small distances between interacting particles.
It is crucial for the various nuclear fusion reactions that generate various energies required for most life forms.

Types of Basic Forces

Based on four basic types of interactions, which explain every action we see around us, there are following four basic forces exist all around us:

Strong Nuclear Force
Weak Nuclear Force
Electromagnetic Force
Gravitational Force

Four Types of Forces — **Four Basic Forces** (Image Credit: online science)

On a visible scale, the Gravitational and Electromagnetic forces have enormous ranges, and both are the foundation for other contact forces. Since both Strong and Weak Nuclear Forces dominate at the subatomic level, they are not directly encountered on the visible scale. Thus, they are effective only over a short range but are essential to the structuring of matter.

4 Fundamental Forces

Fundamental Forces	Strengths	Range	Attraction/Repulsion
Gravitational Force	10⁻³⁸	∞	Attractive only
Electromagnetic Force	10^–2	∞	Attractive and Repulsive
Weak Nuclear Force	10^–13	<10^–18m	Attractive and Repulsive
Strong Nuclear Force	1	<10^–15 m	Attractive and Repulsive

Types of Molecular Force

Molecular forces are attractive forces between atoms or molecules, which cannot show saturation and decrease much more slowly with increasing distance. There are two major types of molecular forces that exist within molecules listed below:

Intramolecular Force
Intermolecular Force

Types of Intramolecular Forces

Types of Intramolecular forces exerted within molecules based their chemical bonding. The classical model of chemistry identifies the following three types of intermolecular forces:

Covalent Bonds
Ionic Bonds
Metallic Bonds

Explain Types of Intramolecular Forces with Example

The following chemical bonds are types of intramolecular forces, distinguished by the degree of charge separation between participating atoms:

Covalent Bonds

It occurs between two interacting non-metals by sharing electrons particles.
Two covalent bonds exist within molecules: polar and nonpolar, depending on the atom’s electronegativity.
If the electronegativity difference between two atoms, then there is a Polar covalent bond, if it is the same electronegativity, then there is Non-Polar covalent bond.

Ionic Bonds

It occurs between two oppositely charged ions, such as negatively charged ions and positively charged ions, called anions and cations, respectively.
A cation can be a metal, and anion can be non-metal.
In the ionic bonds between two atoms, electrons are completely transferred from cation to anion, which results in total charges on the atoms.

**Ionic Bonding** (Image Credit: wikipedia)

Metallic Bonds

In metallic bonding, the metal atoms are closely packed together, and their electrons become separated.
As a result, the separated electrons can migrate freely within the metal to contribute to the conduction.

**Metallic Bonding** (Image Credit: chemistry learner)

Types of Intermolecular Forces

Types of Intermolecular forces exerted between molecules based on their interactions. Three major types of intermolecular forces are listed below from strongest to the weakest:

Dipole-Dipole Interactions
Hydrogen Bonding
London Dispersion Force

Explain Types of Intermolecular Forces with Example

The following interactions are types of intermolecular forces, distinguished by an attraction or repulsion between atoms and neighboring interacting particles.

Dipole-Dipole Interactions

Dipole-Dipole interaction occurs between two polar molecules when they become close to each other.
It is the strongest intermolecular force.
In this interaction, the negatively charged component of one molecule is attracted to the positively charged component of another.
This is a common intermolecular force type since most of the molecules are polar.

For example, Hydrogen Chloride having polar covalent bonds.

Type of Dipole-Dipole Interactions Forces

Ion-dipole interactions

Ion-dipole interaction occurs when an ion meets a polar molecule that has a dipole.
In ion-dipole interaction, the charge of the ion decides which part of the molecule will attract to another molecule and which will repel.
A cation, positive ion would be attracted to the negative portion of the molecule, and an anion, negative ion would be attracted to the positive portion of the molecule.

Hydrogen Bonding

Hydrogen Bonding is the strongest dipole-dipole interaction and the electrostatic bond between Hydrogen on one molecule and Oxygen (or Nitrogen) on another molecule.
This type of dipole-dipole interactions will commonly occur for species matching the pattern X-H …: Y, where the dots denoted the hydrogen bond interaction (H-bond), and X and Y are the common electronegative atoms (N, O, F).
When molecules donate their hydrogen are termed “donor molecules”. On the other hand, the molecules containing lone pairs contributing to Hydrogen bonding (H-bond) are termed “acceptor molecules”.
Hydrogen bond explains the exceptionally high boiling and melting points of compounds like water, H2O, HF.

London Dispersion Force

London Dispersion Force is a weak and short-distance intermolecular force resulting from the movement of the electrons, therefore producing temporary positive and negative charged regions.
The strength of the London Dispersion Force is based on the number of electrons particles the molecule has.
Due to greater polarizability, the larger atoms in non-polar molecules exhibit a more significant London dispersion force.
Therefore, for nonpolar molecules, London dispersion force increases, providing greater intermolecular contact surface area.
It is the Van der Waals Force explains the universal attraction between objects, gases’ physical adsorption, and condensed phases’ cohesion.

For example, Bromine molecules have more electrons than chlorine molecules; hence the bromine molecules have stronger London dispersion forces than chlorine molecules; as a result, a higher boiling point for bromine, 58⁰C, than chlorine, –34⁰C.

**London Dispersion Bonding** (Image Credit: chemistry learner)

Internal Force Vs External Force

Internal Force	External Force
When a force acts on the object from within the structure, it is known as the Internal force.	When a force acts on the object from outside, it is known as External force.
It resulted due to the interactions of particles within a system.	It resulted due to the interactions between a system with its surroundings.
It resist the motions of particles.	It caused the motion of the object.

Types of Internal Force

The four types of internal forces are classified based on the direction in which they act are listed below:

Compression: A force that compresses or squeezes that material together, often making materials shorter.
Tension: A force that extends or stretches the material apart to enlarge or lengthen.
Shear: A force that pushes the objects in opposite directions
Torsion: A force that twists the objects.

Four Main Types of Resistance Forces

Types of resistance forces are the vector sum of numerous forces that resist the motion of the moving objects. The four main types of resistance forces are listed below:

Objects with mass, inertia, and momentum
Friction
Gravity
Air resistance

What is Inertia?

Inertia is the property of an object that makes a stationary or resting object remain at rest, and a moving object will continue moving.

“An object’s tendency to oppose or resist the change in its motion called object’s inertia”

How to Overcome the Inertia of an Object?

Since the inertia of an object depends on its mass, it must be overcome by a net external force (mg) acting on the object. The smaller the object’s inertia, the lesser the force is required to accelerate it. An applied force will make an object move, or due to resistance, it will slow or stop the object that is already moving.

Let’s take an example of a sliding box that slows down on its own.

Here is the first thing to understand that a net external force acting on the sliding box makes it slow down. Without the net force, the box would proceed to slide with constant motion. So the real question is, which type of force acts on the box to overcome its inertia and slow it down? This force is called friction.

**Inertia Example** (Image Credit: texasgateway)

The frictional force is an external contact force that resists the object’s motion by acting opposite to its direction. Hence, the frictional force is the external force that makes a sliding box slow down.

FREQUENTLY ASKED QUESTIONS (FAQs)

What are the two major types of forces?

Ans: The two major types of forces are given below depending on whether they result from contact or non-contact between two interacting objects:

Contact Force
Non-Contact Force

What are the different types of forces in physics? (numbering not reqd for list)

Ans: There are at least ten different kinds of forces exist in the physics as follows:

Gravitational Force
Frictional Force
Electromagnetic Force
Air Resistance Force
Applied Force
Normal Force
Spring Force
Electrostatic Force
Tension Force
Nuclear Force

What are the different types of forces, and how do they all work?

Ans: The following four different types of forces which held for the atomic particles to decay to the motion of whole galaxies:

Gravitational Force
Strong Nuclear Force
Weak Nuclear Force
Electromagnetic Force

They all work by an attraction or repulsion between two interacting objects and are defined through interactions between particles and fields.

How accurate is it to say there are only 4 types of forces in the universe: gravity, weak nuclear force, electromagnetic force, and strong nuclear force?

Ans: The force of gravity, weak nuclear force, electromagnetic force, and strong nuclear force are four basic or fundamental forces in the universe.

These four fundamental forces are responsible for all the planets in the universe spinning, and the burning of the sun and stars act a distance from each planet. Also, they interact with every element to describe the universe.

Which type of force is tension?

Ans: Tension force is exerted on any object when it is in physical contact with another object.
Therefore, the tension force is the contact force.

Air resistance is what type of force?

Ans: Air resistance force is exerted on any object when it is in physical contact with another object.
Therefore, the air resistance force is the contact force.

Friction is what type of force?

Ans: Friction is exerted on any object when it is in physical contact with another object.
Therefore, the friction is the contact force.

What type of force is the lifting of water from the well?

Ans: Two types of contact forces is required to lifting of water from the well:

Muscular or Applied Force
Frictional Force.

When applied or muscular force on the pulley through the rope to lifting with water from the well, it is counterbalanced by the friction force between rope and lift or pulley of the wheel.

Which type of force is available for every other force?

Ans: Gravitational force or force of gravity is available for other contact-non contact forces.

Whether large or small, every object exerts a gravitational force, an invisible natural force on another object.

Which is the weakest force?

Ans: The gravitational force has enormous ranges; hence get its strength weaker with distance.

Therefore, the gravitational force or force of gravity is the weakest force.

What type of force is gravity?

Ans: Force of gravity is exerted on any object when it is not in physical contact with another object.
Therefore, the force of gravity is ‘Non-Contact Force’ and also known as ‘Fundamental Force’ or ‘Types of Action at a distance force’.

Is weight a type of force?

Ans: The weight of any object = mg

Because of the presence of acceleration to gravity ‘g’, the weight of any object is known as the gravitational force, type of non-contact force.

What type of force is magnetism?

Ans: Magnetism is exerted on any magnetic object when it is not in physical contact with another object.

Therefore, the magnetism is the non-contact force, and also known as ‘Fundamental Force’ or ‘Types of Action at a distance force’.

Which forces are acting on an oil droplet?

Ans: Two forces are acting on an oil droplets are:

Gravitational Forces (pulls down)
Air Resistive Force (pull downward)

Which are the types of forces between molecules?

Ans: Two types of molecular forces between molecules are:

Intramolecular Forces
Intermolecular Forces.

What are the differences in terms of intramolecular and intermolecular forces?

Ans: The difference between intramolecular and intermolecular forces is:

Intramolecular forces exist inside a molecule to hold atoms together, whereas intermolecular forces exist between two molecules.

The strongest of attractive forces is which type?

Ans: The nuclear force, one of the attractive basic forces, binds the atomic particles together.

Therefore, dipole-dipole interactions force, a subtype of nuclear force, is the strongest attractive force.

What is the strongest intermolecular force?

Ans: The intermolecular force is strongest when the molecules become close to each other.

Therefore, the dipole-dipole interaction is the strongest intermolecular force between molecules.

What types of forces are acting between Gas molecules?

Ans: Since gas molecules move freely from each other, there are no forces between gas molecules.

Which intermolecular forces are displayed by Hydrogen bromide HBr?

Ans: Hydrogen Bromide HBr has a polar covalent bond due to sharing of unequal valence electrons.
Therefore, Hydrogen Bromide HBr displayed both dipole-dipole interaction and london dispersion forces due to the presence of valence electrons.

What type of intermolecular force is Water Molecules H₂O?

Ans: Water molecules H₂O contain a hydrogen molecule H₂ along with lone pair molecules such as oxygen O.
Therefore, a water molecules H₂O having a hydrogen bonding intermolecular force.

What type of intermolecular force is Carbon Dioxide Molecules Co₂?

Ans: Carbon Dioxide CO₂ is a non-polar molecular which has two polar ponds. But their dipoles cancel each other as it is in the opposite direction.
Therefore, Carbon dioxide CO₂ having only a London dispersion force.

What types of intermolecular forces exist between Hydrogen Iodide Hi and Hydrogen Sulphide H₂S?

Ans: Hydrogen Iodide Hi and Hydrogen Sulphide H₂S has a polar covalent bonds due to sharing of unequal valence electrons.
Therefore, Hydrogen Iodide Hi and Hydrogen Sulphide H₂S displayed dipole-dipole interaction and dispersion forces due to the presence of valence electrons.

What type of intermolecular forces exists between Hydrogen Bromide HBr and Hydrogen Sulphide H₂S?

Ans: Hydrogen Bromide HBr and Hydrogen Sulphide H₂S has a polar molecules in which positive pair of one molecule is attracted to negative pair of other.

Therefore, a dipole-dipole interactions force is exists between Hydrogen Bromide HBr and Hydrogen Sulphide H₂S

What type of intermolecular force holds atoms together in a crystal?

Ans: When the molecules don’t have any net charges or dipole moments, only the Van der Walls force acting on it.
Hence, Van der Walls force is an intermolecular force that holds atoms together in a crystal.

What are types of resistance forces?

Ans: The four types of resistance forces are:

Friction Force
Force of Gravity
Air Resistance Force
Objects with mass, inertia, and momentum

What are four types of internal forces?

Ans: The four types of internal forces are:

Compression
Tension
Shear
Torsion

Which force is required to overcome the inertia?

Ans: The frictional force is an external contact force that resists the object’s motion by acting opposite to its direction.

Hence, the frictional force is the external force that makes a sliding box slow down.

Also Read:

Manish Naik

Hello, I’m Manish Naik completed my MSc Physics with Solid-State Electronics as a specialization. I have three years of experience in Article Writing on Physics subject. Writing, which aimed to provide accurate information to all readers, from beginners and experts.
In my leisure time, I love to spend my time in nature or visiting historical places.
Looking forward to connecting you through LinkedIn –