Friction is any force that acts to oppose the motion. Friction occurs when two surfaces are in relative motion. It can be classified based on the mode of contact, state of matter of the surface, type of sliding object, and state of motion of the object. Let’s have a look at the 9 main types of friction with examples.
Types of Friction:
- Static friction
- Kinetic friction
- Rolling friction
- Sliding friction
- Dry friction
- Fluid friction
- Air resistance
- Skin friction
- Quantum friction
For more detailed examples of friction with respect to different types of friction, you can read our post on 50 examples of friction. Let us look at each one of these types of friction in detail with definitions and with some everyday examples of these friction types.
Static friction:
Static friction is one of the types of friction experienced by an object when at rest. The maximum force required to make an object move is called limiting friction. You can read more about these types of friction in our detailed post about static friction.
Some everyday examples of static friction:
- A car parked on a hill will not slide because of the static friction stopping it.
- Your hat will not suddenly fall off your head because of the static friction.
- The nail fixed on wood or wall remains in its place and won’t move unless disturbed.
- Your elastic bands stay on your hair due to static friction.
You can read about more examples of static friction in this blog post titled “20 examples of static friction“.
Which is the greatest type of friction?
Static friction is the greatest types of friction. And, air resistance or fluid friction is the weakest type of friction. All friction types depend on various factors that affect friction. So, the exact value may vary from situation to situation.
Kinetic friction:
Kinetic friction is the opposing force in action when an object is in motion. In other words, it is the minimum force required to keep an object in motion. Kinetic friction is generally lesser in value compared to static friction.
Image by Kahl Orr from Pixabay
Some everyday examples of kinetic friction
- Train to move on rails: There is an opposing force in action because the wheels slide over the rails.
- While walking we experience kinetic friction between our feet and the ground. The friction value depends on our shoe type and also the type of surface.
- Friction experienced while sliding down a kid’s slide is an example of kinetic friction.
How friction can be categorized?
Types of friction based on:
- Based on the state of motion: Static friction and kinetic friction
- Based on the state of matter: Dry friction, fluid friction, and air resistance
- Based on the mode of contact: Sliding friction and rolling friction
- Other subcategories of friction: are quantum friction, drag, pipe friction, and skin friction
What causes friction?
There are many factors that lead to friction:
- Chemical bonding between surfaces: Weak Van der Waal forces or some strong chemical bonding might exist between the object and the surface.
- Irregularities in the surfaces cause interlocking at the microscopic scale
- The shape of the object may obstruct flow as in the case of fluid friction
- The electrostatic or magnetic fields might also cause friction.
You can read more about this here in this post on factors affecting friction.
Sliding friction:
Friction can be categorized based on the mode of contact. Sliding friction occurs when two bodies slide over each other. This type of friction has the greatest value among other types of friction. The interlocking of irregularities is high due to sliding, hence the friction value is also greater. It is almost impossible to avoid this type of friction in our daily lives. You can this video on life without friction to learn more.
Examples of sliding friction in our daily lives:
- Walking on a road
- brushing your teeth
- mopping of floor
- Skiing
- Carrom
Rolling friction:
Rolling friction occurs when one body rolls over another. When an object rolls, the contact with the surface is the least. This type of friction is the least among dry friction. In this type of friction, the object rolls rather than slides. The value of friction is low but the control over the object is less.
Examples of rolling friction in our daily lives:
- Roller skates
- Railway trains
- Bullock cart
You can read more in our detailed post on rolling friction.
Fluid friction:
The friction experienced by a body in contact with the fluid is called fluid friction. The value of fluid friction is generally less than dry friction. Air resistance can also be considered a part of fluid friction. You can see water splash off a high-speed boat, this is due to fluid friction. Fluid friction can also be internal in nature like friction between the molecules of honey.
What are the laws of fluid friction?
- Fluid friction depends on the nature of the fluid.
- Fluid friction always acts opposite to the direction of motion.
- Fluid friction depends on the shape and contact area.
- Fluid friction is affected by the speed of the sliding object.
Some everyday examples of fluid friction:
- A speed boat moving on the sea
- Swimming in water
- Movement of fishes and corals in water
Dry Friction:
The term dry friction is generally used to signify that the sliding object and the sliding surfaces are solids. Dry friction is always greater than other friction types. Dry friction can be further classified into rolling and sliding friction based on the mode of contact. It can be classified into static and kinetic friction based on the state of motion. Dry friction is one of the important types of friction.
Some everyday examples of fluid friction:
- Rubbing of hands to produce heat
- Moving cars on roads
- Rubbing of trees producing forest fires
What are the laws of dry friction?
- Friction is directly proportional to the normal force on the sliding object
- Friction always acts in a direction opposite to the force applied
- Dry friction is independent of the shape and area of contact
- It depends on the nature of the surfaces (coefficient of friction)
You can read more about this in our post on factors affecting friction.
Air resistance:
It the friction experienced by a body when in contact with a gaseous substance. This is the weakest type of friction. But generally, air friction or air resistance is considered a type of fluid friction. You can experience this friction by just putting your hands out while riding a bike. You can feel the air rushing through your hands. This is air resistance
Examples of air resistance in our daily lives:
- A windsock showing the direction of air
- Flying an airplane
- Flying of birds and bats
Skin friction:
It is a type of friction experienced at the surface of a solid or fluid when in motion. Pipe friction is a very good example of skin friction. When a fluid moves through a pipe, the part of the fluid in the middle will experience the least friction. Whereas the part of fluid at the surface will experience friction while sliding across the pipe surface. It s also called Skin Friction Drag.
Image by analogicus from Pixabay
Examples of skin friction:
- The flow of water in a pipe
- Friction is experienced by river water across the riverbed.
Quantum friction:
This is a new type of friction defined for a quantum particle. It can be considered as electromagnetic field-induced friction acting on an uncharged polarizable object to stop relative motion.
Which is the most commonly encountered type of friction?
Dry friction is the most commonly encountered type of friction on Earth. As on the planet Earth due to gravity, we are all moving relative to the surface of the Earth. Since most of the Earth is a solid landmass it is obvious that we encounter dry friction very frequently. Sliding friction is also very common as most of things slide compared to roll. And since most of the things on our planet are stationary due to gravitational pull, static friction is also very common.
If we were all flying then air resistance would be the most common type of friction.
Which is the least encountered type of friction?
The least known types of friction include skin friction and quantum friction. Even air resistance is also not very frequently encountered unless you are flying or experiencing wind of some speed.
