What are the factors that affect friction? Explain in detail.
Answers
Answer:
Friction originates when two surfaces slide over each other. There are many factors that affect friction. The frictional force is based on the interlocking mechanism and also on other factors like pressure and design. Let us understand the factors affecting friction with examples, quizzes, and links to research articles.
What are the factors affecting friction?
Roughness/smoothness of the sliding object
Roughness/smoothness of the surface
Shape/design of the object
Normal force acting upon the sliding bodies
Dry friction is independent of the surface area of a contact
Type of friction involved(rolling/sliding)
Sliding surface’s state of matter (solid/fluid)
Friction force depends mainly on the above listed factors, lets discuss them in detail.
1. The smoothness of the sliding object
irregularity of the object is a factor affecting friction
Friction is directly proportional to the roughness of the object
Smooth surfaces slide over surfaces easily compared to rough ones. When you look at the microscopic scale you can notice the irregularities in the surface which hinder sliding. Thus more the roughness higher is the friction
Snow-covered surface offers very little friction. Cyclists use tires with high irregularity (grip) to increase friction with the surface.
2. The smoothness of the surface
the interlocking mechanisim which is a main factor affecting friction
It is impossible to have perfectly smooth surfaces. Each surface will have its own roughness. This roughness combined with the roughness of the sliding object will give rise to friction.
3. The force between the two bodies in the normal direction (perpendicular to sliding direction)
Friction is directly proportional to normal force applied
Friction is directly proportional to normal force applied
The force in the normal direction (perpendicular to the sliding plane) will increase the interaction between the surface thus increasing the friction. Friction is thus directly proportional to the normal force applied. [f = μ * N, where μ is the coefficient of friction]
normal force(weight) is a factor affecting friction
Friction is directly proportional to the weight of an object
The weight of any object is the commonly observed force in the normal direction. So, friction is directly proportional to the weight of an object. According to the animation above it is easier to push a light object compared to a heavy object of the same material.
4. Friction also depends on the design of an object
Friction exists in liquid and gases also. Friction is less in air or water compared to when sliding against a solid surface like road.
The shape/design of an object affects friction
The streamlined body of dolphins help them to reduce friction in water.
The design of aircraft and fishes are streamlined in order to avoid friction.
5. Friction is independent of the area contact
Friction is directly proportional to the normal force but is independent of the area of contact. [f = μ * N, where μ is the coefficient of friction]
6. Type of friction involved (rolling/sliding)
Rolling friction is always less than sliding friction. The introduction of wheels is also a factor that can reduce friction drastically. Try sliding your suitcase compared to a stroller bag, you can feel the ease of movement due to the drastic reduction in friction. Example: roller skates reduce friction and hence allow us to move faster compared to normal shoes.
7. Sliding surface’s state of matter (solid/fluid)
Fluid friction is always generally less than dry friction. Fluid friction is the friction between an object and a fluid(liquid or gas). Example: Lubrication works on the principle of fluid friction, where a viscous fluid acts a layer between two sliding surfaces and reduces the friction between them.