# Frictional Force - Definition, Types, & Problems | Turito (2023)

## Frictional Force

Frictional force can be defined as a force that opposes motion when the surface of a body comes into contact with that of another body. Friction force decreases the mechanical advantage of a machine, or it decreases the ratio of output to input. Around one-quarter of its energy is used by an automobile in limiting friction force, but the friction in the tires allows the car to stay on the road, and that in the clutch makes it possible for us to drive.

Ranging from matchsticks to machines to molecular structures of every simple and complex object, friction is one of the most prominent processes in the physical world. This article will discuss the friction force and its types in detail.

### What is friction force?

What is friction force? The force generated by two surfaces of two objects when they come in contact and slide against each other is called the force of friction. The factors affecting frictional force include:

• The frictional force is significantly affected by the texture of the surface and the quantity of force that propels them together.
• The force of friction is affected by the position and angle of the object.
• If we place an object flat against another object, then the force of friction is equal to the object’s mass.
• If we push an object against the surface of another object, then the amount of the frictional force is increased, which becomes higher than the object’s weight.

### Calculating the Force of Friction

What is friction force calculation? The maximum frictional force applied on an object by a surface can be easily calculated by the following formula:

Ffrict = µ • Fnorm

Below are given the systematic steps that you can follow while dealing with calculations based on the frictional force:

### Determine the Normal Force

The normal force exerted on a body in contact with another stable body is the support force, and in most cases, it can be simply described by the following friction force formula:

N = mg

(Video) Frictional Forces: Static and Kinetic

Where,

M is the mass of the object

G is the acceleration due to gravity

If the surface is inclined, the strength of the force is decreased with the extent of inclination; therefore, the friction force formula becomes:

N = mg cos(θ)

Where,

The angle of inclination of the surface is θ

The force of a normal type of 2 kg wood block sitting on a surface is calculated in a simple calculation as,

(Video) Static Friction and Kinetic Friction Physics Problems With Free Body Diagrams

N = 2 kg × 9.8 N/kg = 19.6 N

### Calculating Frictional Force

The friction force formula is given by:

F = μN

Suppose we consider a wood block weighing 2 kg lying on a table to be moved from rest. We consider the static friction coefficient in this case, which is 00.5 in the case of wood.

The normal force can be calculated with the given details,

N = 2 kg × 9.8 N/kg = 19.6 N

As we now have the values of static friction coefficient and normal force, the frictional force can be calculated as follows:

F = 0.5 × 19.6 N = 9.8 N ### Are frictional forces of different types?

Different types of frictional forces exist, such as kinetic frictional force, static frictional force, sliding frictional force, and rolling frictional force. The frictional force taking place between gases and fluids is called fluid friction. Following is the broad classification of the frictional force:

(Video) FRICTIONAL FORCE ll KINDS OF FRICTIONAL FORCE

• Static friction
• Dry friction
• Rolling friction
• Kinetic friction
• Dry friction
• Fluid friction

### Dry Friction

The reaction between two solid bodies is described by dry friction. When the two solid bodies are in motion, their friction is described as kinetic friction. When they are not in motion, it can be described as static friction. Both kinetic and static frictional forces are proportional to the normal force between two solid objects.

Different coefficients of friction model the interaction of different substances. This means that certain substances are more resistant to movement as compared to others when the magnitude of normal force between them is the same. The values for each of these can be determined experimentally.

### Rolling Friction

Rolling friction comes into play when a ball, wheel, or cylinder rolls freely over a surface, as in the case of the ball and bearing rollings. The distribution of energy involved in the twisting of the bodies involved is the main cause of friction in rolling. If we roll a hardball on a level surface, the surface is indented at the points of contact while the ball is somewhat packed down.

The compression or elastic bend created at the main point of contact is interference to motion that is not entirely compensated as the substances revert back to their typical shape at the trailing section. The internal losses in the two substances are parallel to those that prevent a ball from bouncing back to the level of its release. The sliding friction coefficients are usually 100 to 1,000 times greater than the rolling friction coefficients for corresponding materials.

### Examples of Rolling Friction

Rolling friction is a type of dynamic or kinetic friction that comes into play when one object rolls over another. For instance, when a circular disc, a ring, a sphere, or a wheel rolls over the surface, rolling friction is the force opposing its motion. Other examples of rolling friction are:

• A basketball that is rolling on a court comes to a halt after a while.
• A tire or skateboard wheels rolling on the road are also examples of rolling friction.
• The motion of vehicles is affected by factors like size, shape, and weight. Suppose a heavily loaded twenty-wheeler truck will have greater rolling friction than a TATA Nano Car.
• Use of paint rollers in the painting of the walls.

### Fluid Friction

The force obstructing the flow of fluid is called fluid friction. In this situation, resistance is provided by the fluid between two surfaces. If the resistance is offered by both the surfaces, it is called high dense and can be generally called greasy. Examples of fluid friction include:

• Lubrication of the door hinges causes smooth functioning of the door and avoids creaking sounds while opening and closing them.
• When a ball is dropped in a bucket full of water, the water splashes out of the bucket due to the buoyancy of the fluid.

## Problems with Frictional Force

1. A huge ice block is pulled across a frozen lake that has a mass of 300 kg. There is a small frictional force between the two ice surfaces equal to μk = 0.05. Calculate the frictional force acting on the ice block.

Solution: The normal force acting on an object resting on a flat surface can be given by the formula N = mg. This can be used to calculate the frictional force as follows:

Ff =μN

Ff =μmg

In the above equation, if we substitute the data, we get:

Ff =0.05 × 300 kg × 9.8 m/s2

(Video) Static & Kinetic Friction, Tension, Normal Force, Inclined Plane & Pulley System Problems - Physics

147 kg-m/s2 or 147 N.

The frictional force acting in the opposite direction as we pull the ice block across the lake is 147 N.

1. A boat is pushed by a man on the shore to get water. The frictional coefficient between the mud and the boat is given by μ = 0.400. Calculate the magnitude of frictional force acting on the boat if the boat has a mass equal to 40 kg.

Solution: The normal force acting on an object on a flat surface is N = mg.

This information can be used to calculate frictional force as follows:

F = μN F = μ mg

If we substitute the data in the formula, we get

F = (0.400)(40.0 kg)(9.80 m/s2)

F = 156.8 N

Therefore, the force of friction acting on the boat equals 156.8 N.

### Conclusion

If you have gone through the whole discussion thoroughly, most of your doubts on the topic of frictional force will have been cleared and you can hopefully solve a lot of problems based on the topic. Keep practicing different types of problems related to the topic to gain a fundamental understanding of its concepts.

### 1.What is static friction?

The frictional force is experienced when we try to bring a stationary body to motion on a surface without stimulating a relative motion across the surface, and the body is called static frictional force.

(Video) Types of frictional forces with examples

### 2.Is frictional force a scalar or a vector quantity?

As frictional force involves both magnitude and direction, it is a vector quantity.

### 3.How to find the right coefficient?

The coefficient chosen depends on the object and the specific situation. The coefficient of static friction is used if the object is not moving across the surface, while the coefficient of sliding friction is used if the object under consideration is moving. The coefficient is also affected by the type of materials used. For instance, the coefficient is 0.6 if there is a block on a brick surface, while it ranges from 0.25 to 0.5 if it is on a block of clean wood.

## FAQs

### What is friction force and its types? ›

Friction is the force that opposes the motion of a solid object over another. There are mainly four types of friction: static friction, sliding friction, rolling friction, and fluid friction.

What are the 5 types of friction? ›

Types of Friction
• Static Friction.
• Sliding Friction.
• Rolling Friction.
• Fluid Friction.
9 Feb 2021

What are the 3 types of frictions? ›

The reason we are able to control cars at all is because of friction between the car's tires and the road: more accurately, because there are three kinds of friction: rolling friction, starting friction, and sliding friction.

Which type of force is frictional force? ›

Friction is a type of contact force. It exists between the surfaces which are in contact.

What are the 2 types of friction? ›

There are two main types of friction: static and kinetic, according to the journal The Physics Teacher (opens in new tab). Static friction operates between two surfaces that aren't moving relative to each other, while kinetic friction acts between objects in motion.

What are the four main types of friction? ›

Different types of motion of the object gives rise to different types of friction. Generally, there are 4 types of friction. They are static friction, sliding friction, rolling friction, and fluid friction. The next sections will explore these forces and when they are applied.

What is friction explain? ›

friction, force that resists the sliding or rolling of one solid object over another. Frictional forces, such as the traction needed to walk without slipping, may be beneficial, but they also present a great measure of opposition to motion.

What are the 8 forces? ›

Action-at-a-Distance Forces
• Applied Force.
• Gravitational Force.
• Normal Force.
• Frictional Force.
• Air Resistance Force.
• Tension Force.
• Spring Force.

What is friction and example? ›

Walking – When we walk on the ground or the floor, it is the frictional force that is responsible for holding our feet to the ground. On slippery surfaces or ice, the friction present is less, which is why we tend to slip on these surfaces.

What are laws of friction? ›

The friction of the moving object is proportional and perpendicular to the normal force. The friction experienced by the object is dependent on the nature of the surface it is in contact with. Friction is independent of the area of contact as long as there is an area of contact.

### What causes friction? ›

Friction is a resistive force that occurs when two bodies in contact move relative to one another. Causes of friction: Adhesion between body surfaces: Adhesion is the molecular force that occurs when two materials come into close contact.

What are the uses of friction? ›

10 examples of friction in our daily life
• Driving of a a vehicle on a surface.
• Applying brakes to stop a moving vehicle.
• Skating.
• Writing on notebook/ blackboard.
• Flying of aeroplanes.
• Drilling a nail into wall.
• Sliding on a garden slide.

Which depends on frictional force? ›

Friction is a force that opposes the relative motion between two surfaces in contact. The cause of friction is the interlocking within the irregularities of the two surfaces. As the interlocking is more in rough surfaces, friction is on these type of surfaces. Hence, friction depends on the roughness of the surface.

Which is unit of force? ›

The SI unit of force is the newton, symbol N. The base units relevant to force are: The metre, unit of length — symbol m. The kilogram, unit of mass — symbol kg.

What are effects of friction? ›

Effects of Friction

It produces heat, that helps in heating parts of any object or to warm ourselves. It also causes loss in power. It produces noise during any kind of operation. It's because of friction that we're able to walk, run, play, etc.

Who discovered friction? ›

The classic laws of sliding friction were discovered by Leonardo da Vinci in 1493, a pioneer in tribology, but the laws documented in his notebooks were not published and remained unknown. These laws were rediscovered by Guillaume Amontons in 1699 and became known as Amonton's three laws of dry friction.

What is kinetic and static friction? ›

Static and Kinetic Friction. If two systems are in contact and stationary relative to one another, then the friction between them is called static friction. If two systems are in contact and moving relative to one another, then the friction between them is called kinetic friction.

What are 20 examples of friction? ›

List Ten Examples of Friction in Our Daily Life
• Walking.
• Skating.
• Writing with a pen.
• Driving a vehicle.
• Flight of aeroplanes.
• Lighting a matchstick.
• Sliding on a slippery surface.
• Drilling a nail in the wall.
10 Aug 2022

What is angle of friction? ›

Angle made by the resultant of normal reaction and limiting friction with the normal reaction is called the angle of friction. The coefficient of static friction is equal to the tangent of the angle of friction.

What are the 4 strongest forces? ›

Ordered from strongest to weakest, the forces are 1) the strong nuclear force, 2) the electromagnetic force, 3) the weak nuclear force, and 4) gravity.

### What are the 3 elements of force? ›

Forcethese are the 3 elements, that is the magnitude of force, direction, force and the point of action.

What are the 6 types of force? ›

Types of Forces:
• Tension Force.
• Spring Force.
• Normal Force.
• Air resistance Force.
• Frictional Force.
• Force of Gravity.
• Applied Force.

What are the 10 advantages of friction? ›

...
Without friction we are handicap.
• It is becomes difficult to walk on a slippery road due to low friction. ...
• We can not fix nail in the wood or wall if there is no friction. ...
• A horse can not pull a cart unless friction furnishes him a secure Foothold.
• We can write on a paper or on a board.

What are all 4 forces? ›

fundamental force, also called fundamental interaction, in physics, any of the four basic forces—gravitational, electromagnetic, strong, and weak—that govern how objects or particles interact and how certain particles decay. All the known forces of nature can be traced to these fundamental forces.

What are the 5 main forces? ›

According to Porter, there are five forces that represent the key sources of competitive pressure within an industry They are:
• Competitive Rivalry.
• Supplier Power.
• Threat of Substitution.
• Threat of New Entry.

What are the 4 different forces? ›

If you remember any of the physics you learned in school, it's possible you may remember that there are four fundamental forces of nature. They are in no particular order gravity, electromagnetism, the weak nuclear force and the strong nuclear force.

What is advantage of friction? ›

Advantages of friction are below: Automobile brakes employ friction just to stop the vehicle. It assists us in walking on the earth. Friction causes asteroids or stones to disintegrate throughout the atmosphere prior to actually approaching the entire planet (Earth).

What are the properties of friction? ›

Properties of frictional forces:

Frictional force always acts parallel to two planes in contact with each other and in a direction opposite to that of relative motion of the two bodies. 2. Frictional forces are caused due to intermolecular interactions between the bodies.

How can we reduce friction? ›

Friction can be reduced by: lubricating the surfaces. use of ball bearings (i.e. replacing sliding friction with rolling friction) streamlining the body.
1. lubricating the surfaces.
2. use of ball bearings (i.e. replacing sliding friction with rolling friction)
3. streamlining the body.

Who increases friction? ›

To increase friction, the surfaces in contact have to be made rough. The two surfaces in contact can also be pressed harder to increase force between them. Use of adhesive materials that stick surfaces , also increases friction between them.

### What increases friction? ›

Friction can be increased by following methods: Making the surfaces rough. By pressing the surfaces harder against each other (by increasing normal force). By removing the lubrication between the surfaces in contact.

What are 5 causes friction? ›

Friction is a force that resists the relative motion between two objects or materials. The causes of this resistive force are molecular adhesion, surface roughness, and deformations. Adhesion is the molecular force resulting when two materials are brought into close contact with each other.

How is friction harmful? ›

A lot of heat is generated by friction in various mechanical parts, which wastes energy as heat. Restricts motion, requiring more energy to overcome it. Making noise while operating a machine wastes energy and is annoying. Friction between tree branches is what ignites forest fires.

What are the effects of force? ›

Effects of force with examples :
• It can make a stationary object move. Example: pushing a box at rest on the table brings the box in motion.
• It can stop a moving object. ...
• It can change the speed of a moving object. ...
• It can change the direction of a moving object. ...
• It can change the shape or size of an object.

Does friction depend on speed? ›

Friction and Velocity

While this is approximately true for a wide range of low speeds, as the speed increases and air friction is encountered, it is found that the friction not only depends on the speed, but upon the square and sometimes higher powers of the speed.

Does frictional force depend on size? ›

Friction is independent of shape and size of body .

Does friction depend on weight? ›

Frictional force between two objects also depends on the factor that how much an object is pressed against the other object or surface. Since heavier the object more it will press against the surface, frictional force is also dependant on weight of the object.

What is the SI unit of friction? ›

The correct option is C Newton. Friction is a type of force that opposes relative motion between two objects. Hence, friction will have the same unit as force. SI unit of force is newton (N).

How do u calculate force? ›

What is the formula for force? The force formula is defined by Newton's second law of motion: Force exerted by an object equals mass times acceleration of that object: F = m ⨉ a. To use this formula, you need to use SI units: Newtons for force, kilograms for mass, and meters per second squared for acceleration.

What is meant by 1 newton? ›

newton, absolute unit of force in the International System of Units (SI units), abbreviated N. It is defined as that force necessary to provide a mass of one kilogram with an acceleration of one metre per second per second.

### What is the meaning of friction force? ›

Frictional force refers to the force generated by two surfaces that contact and slide against each other. A few factors affecting the frictional force: These forces are mainly affected by the surface texture and the amount of force impelling them together.

What is friction force Class 11? ›

The force, which opposes the motion of one body over the other in contact with it, is called frictional force.

How many types of forces are there? ›

There are 2 types of forces, contact forces and act at a distance force. Every day you are using forces. Force is basically push and pull. When you push and pull you are applying a force to an object.

What is importance of friction? ›

Friction can slow things down and stop stationary things from moving. In a frictionless world, more objects would be sliding about, clothes and shoes would be difficult to keep on and it would be very difficult for people or cars to get moving or change direction.

What are 9 force types? ›

Action-at-a-Distance Forces
• Applied Force.
• Gravitational Force.
• Normal Force.
• Frictional Force.
• Air Resistance Force.
• Tension Force.
• Spring Force.

Which is law of friction? ›

THE laws of static friction are usually described as: (1) F = μR, which governs the relation between limiting frictional force F and normal reaction R; and (2) the coefficient of friction μ is independent of the apparent area of contact.

What are the 11 types of forces? ›

Types of Forces:
• Tension Force.
• Spring Force.
• Normal Force.
• Air resistance Force.
• Frictional Force.
• Force of Gravity.
• Applied Force.

What are the 5 effects of force? ›

Effects of force with examples :
• It can make a stationary object move. Example: pushing a box at rest on the table brings the box in motion.
• It can stop a moving object. ...
• It can change the speed of a moving object. ...
• It can change the direction of a moving object. ...
• It can change the shape or size of an object.

What is called force? ›

In physics, a force is an influence that can change the motion of an object. A force can cause an object with mass to change its velocity (e.g. moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a push or a pull.

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