Static Friction

Introduction

There are numerous kinds of friction out there and one such friction is static friction which tends to keep an object in a state of rest. This friction is faced by people when they try to put the body in a state of motion over a surface. This force however does not trigger a movement between a body and the surface it is on. It can be termed as a force of friction that balances the force that is being applied to the object for a particular duration.

Static Friction − Definition

Friction is a force that hinders or resists the movement of a solid body. The static friction is associated with the force that hinders the motion of the object that courses along a particular path. This is noted by people when they tend to move a stationary object over a plane without engaging the body in a relative motion with the surface it is on.

For example, a towel that hangs on a rack or a car that is parked on a hill encounters static friction. A book kept on a table experiences static friction.

According to Marques et al. (2019), this is a force of friction that accurately balances the applied force of a stationary object for a particular frame of time. This frictional force is stated to be a self-regulating force which implies that the static friction will be equal and opposite to the force that is being imparted upon the body.

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Static Friction: Formula

The static friction formula is written as F = $\mathrm{\mu}$N, where F is the static force of friction and M is the coefficient of static friction and N is the normal force or it can also be termed as the force of contact.

It is the force of friction that exists between the surface of an object and the surface of the path it is lying on and there is no existing motion in between them. Thus in this case the object and the surface are in stationary motion and when the object starts moving, and then the kinetic force of friction comes to existence. In the case of static friction, the intensity with which the body grips the surface of the plane it lies on is denoted by the numerical value that is termed as coefficient of Friction.

The relative force that helps an object to lie on the surface in a static state without falling or rolling down is termed normal force which means the force that is being applied by the surface on the object to provide a certain extent of support. In this case, the normal force will act at a certain angle that will be having its component to consider. In case the surface is plain the normal force will be same as the force of the gravity that is being applied to it. The coefficient of this static force is symbolized by the symbol $\mathrm{\mu}$.

In case a car tends to slip down a slope and suddenly a brake is applied to it, that car inches a few distances and then attains a static position. In this case, the static frictional force is being applied to it that helps in halting the slipping of the car.

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Static Friction − Laws

There are two distinct laws associated with static frictional motion. The maximum force of static friction is not free of the area of contact. As opined by Wang et al. (2018), the maximum force of static friction is comparable to the normal force, to elaborate further it can be stated that in case the normal force is increased the maximum amount of external force that the particular object can tolerate without being in motion, also increases.

Limiting Friction: Description

Limiting friction is the highest value that can be associated with the static friction which comes into existence when a particular object is about to move over a surface of a different object. In such a case, due to the external force being higher than the limiting friction the body begins to move. In case a body begins to move static friction is cease to exist and new friction comes into existence which is kinetic friction.

Conclusion

Various kinds of motion exist between a body and a surface and static friction is one such motion that is associated with the friction that an individual faces when they try to put a body in motion over a particular surface without actually putting it in motion a triggering the kinetic friction into existence. Static friction refers to the state of the body up to which it can retain its stationary state after experiencing a certain amount of force.

FAQs

Q.1. What is the cause of friction?

Ans. Friction is caused by the irregularity of the surface on which a particular body is lying. The stickiness of the body and the surface is triggered by certain bonding between the two bodies that lead to adhesion this adhesion determines the intensity of the static friction between the surface of the body and the surface on which the body is lying.

Q.2. What are the two primary laws of limiting friction?

Ans. The limiting friction acts tangentially on two of the interacting surfaces, the limiting friction magnitude is directly proportional to the normal reaction between two interactive surfaces.

Q.3. When is the maximum static friction attained?

Ans. The maximum static friction is attained right before the body attains a state of motion before it begins to move or slide. Mathematically, this value can be obtained from the multiplication of the static friction with the normal force that is being exerted by the surface that is in contact with the body.

Q.4. What is kinetic friction?

Ans. It is the friction that occurs in case a body starts moving over a plane. The kinetic friction is also termed sliding friction or dynamic friction.