Law of Friction

Introduction 

When you throw a ball on a surface, it tends to move for some time with a certain velocity even when there is no force applied in the direction of the ball’s motion. According to Newton’s first law, the ball on the ground should keep on moving; However, it stops after covering a certain distance. The force acting against its motion and causing it to stop is referred to as friction. 

What is Friction? 

In simpler terms, friction can be defined as the traction required to walk without rolling or slipping. Although friction is essential and proven helpful in most situations, there are certain times when excessive friction can lead to discomfort. As per the records, more than 20% of the total engine power in automobiles is consumed to overcome the friction force of the moving parts. 

Law of Friction 

Friction has mainly five different laws. These are as follows – 

• The friction of the object moving is perpendicular and proportional to the normal face. 
• Friction is independent of the contact area.
• The velocity highly determines the kinetic friction. 
• The object experiencing the friction is highly dependent on the nature of the surface it comes in contact with. 
• The static friction coefficient is always greater than the kinetic friction coefficient. 

Factors Affecting the Friction 

Internal factors highly determine the friction in an object. There are two major factors on which the friction force depends – 

1 – The nature of the surfaces that come in contact – Friction is highly determined by the roughness or smoothness of surfaces. If the object’s surface is smooth, then there are higher chances that the friction will be low as there are fewer irregularities. However, if the surface is rough, the friction automatically increases.

2 – The force acting on the surface – When force is applied to an object, the friction increases in spite of all irregularities.

What Leads to Friction 

The major reason behind friction can be described as the irregularities between two surfaces when they come in contact with one another. If one object moves over another one, the surface irregularities engage, leading to high friction. The more the roughness of the surface, the more significant the friction will be. 

Types of Friction

There are mainly four different types of friction- 

• Static friction
• Rolling friction
• Sliding friction
• Fluid friction

Static friction: This can be described as a frictional force that acts between two surfaces if they remain at rest. Examples of static friction include skiing against snow, a lamp resting on the table, and rubbing both hands together to create heat. µs is the coefficient of static friction. 

Here is the equation for static friction – Fs (max) = µs N and Fs ≤ µs N

Where N is normal force.

Rolling friction: Rolling friction can be described as the force that resists the object’s motion on the surface. It is termed the weakest type of friction among all. Examples of rolling friction are moving wheels and log rolling on the ground. µr is the coefficient of rolling friction. 

Here is the equation for rolling friction – Fr = µr. N,

Where N is normal force.

Sliding friction: Sliding friction can be described as the resistance developed between two objects when they slide against one another. An example of sliding friction includes block sliding on the floor. µs is the coefficient of sliding friction. 

Here is the equation for sliding friction – Fs = µs. N

Where N is normal force.

Fluid friction: This can be described as the friction that lies in the fluid layers when they move relative to one another. Examples of fluid friction include swimming, ink flowing from the pen, and so on. 

Applications of Friction 

Here are the significant applications of friction – 

• The pistons motion inside the cylinder is an example of friction. 
• When matchsticks are ignited, they come under the application of friction. 
• Writing books on paper using a pen is only possible because of the available friction. 

Conclusion 

With this, we end our study material on the Laws of friction. In this Introduction to Laws of friction, we studied friction and laws of friction in length. Friction is the traction required to walk without rolling or slipping. Although friction is essential and proven helpful in most situations, there are certain times when excessive friction can lead to download or uncomfort.