Rolling friction

as rolling friction.

The imperfections on the two surfaces in contact generate friction. Even the smoothest surfaces have a huge number of minute imperfections. Irregularities on both surfaces interact with one other. To overcome interlocking, we must exert force while moving any surface. The amount of imperfections on rough surfaces is higher. As a result, the friction force is larger when a rough surface is involved. Static friction is defined as the force necessary to overcome friction when an item begins to move from rest. The force necessary to maintain an item moving at the same speed, on the other hand, is a measure of sliding friction.

Factors Affecting Friction 

The contact points on the box’s surface do not have enough time to latch onto the contact points on the floor when the box begins to slide. As a result, the sliding friction is somewhat lower than the static friction, making it easier to move the box once it is moving rather than starting it. 

The sliding object’s roughness/smoothness: The amount of friction created is determined by the sliding object’s roughness and smoothness. The more wild a thing is, the more friction is created, and hence the object’s mobility is hindered. The object’s smoothness determines how smoothly it can move.

The object’s shape and design: The surface area in touch with the moving surface is determined by the object’s form and design. For example, if the body is streamlined, it will face less frictional force opposing its motion when travelling in water or air than any other form.

Surface roughness vs smoothness: The friction is determined by the characteristics of the surface with which it comes into contact. When the surface is rough, the friction caused by the object’s opposing motion is larger than when the surface is smooth.

The normal force on the acting body: The normal force acting on the sliding bodies affects the force of friction, or the opposing force, which restricts the body’s motion. We normally think of the normal force instead of weight following the Newtonian action-reaction relationship. As the mass or weight of the item increases, the response or normal force created increases.

Friction: A necessary evil 

Consider some of your past experiences. Is a kulhar (earthen pot) or a glass tumbler easier to hold? Would it be easier or more difficult to hold if the tumbler’s exterior surface is greasy or has a small film of cooking oil on it? Consider this: if there is no friction, would it be feasible to hold the glass at all? Consider how difficult it is to move about on a damp, muddy route or a wet marble floor. Imagine not being able to walk at all if there wasn’t any friction.

Without friction, an item that started moving would never stop. Automobiles could not be started, halted, or turned to alter their direction of travel if there was no friction between their tyres and the road. You couldn’t put a nail in the wall or make a knot. There could be no construction without friction. 

Increasing and Reducing Friction

Why do you dust the carrom board with fine powder? You may have observed that a few droplets of oil on a door’s hinges causes the door to glide smoothly. Grease is used as a lubricant to reduce friction on the moving components of a bicycle. We wish to eliminate friction in the following scenarios to boost efficiency. When a thin coating of oil, grease, or graphite is put between the moving parts of a machine, a thin layer is generated, and moving surfaces do not rub against each other directly. The interlocking of imperfections is minimised to the greatest degree possible. As a result, the movement becomes more fluid. Lubricants are chemicals that help to minimise friction.

In the braking systems of bicycles and vehicles, we purposefully enhance friction by utilising brake pads. The brake pads do not touch the wheels when riding a bicycle. However, the friction causes these pads to stop the rim from moving when applying the brakes. As a result, the wheel comes to a halt. You may have noticed kabaddi players rubbing their hands in the dirt to have a firmer grasp on their opponents. Likewise, gymnasts use a gritty material to generate friction on their hands to improve grip.

Coefficient of rolling friction 

The coefficient of this friction is much more difficult to calculate than the coefficient of sliding friction.

“The ratio of the force of rolling friction to the total weight of the item is known as the Coefficient of Rolling Friction.”

The force of rolling friction can be stated as follows:

Fr = μrN

Here  μr  is coefficient of rolling friction

N is the normal force.

Hysteresis

It is described as a system’s current state’s reliance on prior (history) stages of existence. In the preceding example, the tyre’s motion is only conceivable because the tyre was squeezed at an earlier time and was, therefore, able to exert force on the ground. As a result, the current state of the tyre (whether in motion or at rest) is determined by its history. However, because of the tire’s resistive causes of rolling friction, the tyre will never be the same as at the beginning of a deformation cycle, implying that non-elastic processes prevent the tyre from achieving the energy required for complete recovery after the pressure is removed.

Laws of Rolling friction Example 

• If an automobile is solely allowed to travel, it will eventually halt because the friction between the wheels and the road surface allows the vehicle to stop.

• Because there is a better wheel surface to create friction alongside the surface to slow the bike, thicker bike wheels will reduce the bike’s potential speed.

• Heavy-duty trucks have a longer gas range when the tread on the tyres begins to grip. This is due to fewer causes of rolling friction, which allows the vehicle to transfer more quickly and with less resistance.

• A skateboard set will eventually come to a halt on its own if it suffers a minor malfunction due to friction resistance.

Conclusion

The origins of laws of rolling friction are similar to static and sliding friction, but they are somewhat different. Friction, on the other hand, is essential in many practical circumstances. Even though kinetic friction wastes power, it is necessary for promptly halting relative motion. Brakes in machinery and autos make use of it. In the same way, static friction is significant in everyday life. Because of friction, we can walk. On a highly slick road, it is hard for a car to move on a highly slick road. The friction between the tyres and the road generates the necessary external force to accelerate the automobile on a normal road.