Difference between Static Friction and Limiting Friction

Friction exists in between the two objects when there is a contact in between them. There are different types of frictions based on the different factors like the Motion, Force, and the Position of the objects. Here, we are going to discuss about the two types of frictions named Static friction and Limiting friction.

What is Static Friction?

Static friction is defined as when the two objects are in contact and there is movement with respect to each other. In this case, the friction between the two surfaces called Static Friction. The Static friction can only be applicable when there is no relative motion. Static friction provides a certain amount of resistance to move an object we need to apply a force that is greater than the resistance applied by the static friction. When the force applied on the object is not greater than the value of friction or resistance by the static friction the object does not move. The static friction is divided into categories based on the different factors. Mechanical resistance, Chemical resistance, Intermolecular forces these are some of the categories of static friction in different fields at different levels. To calculate the value of friction between the two static objects we need to find the coefficient of friction. The Coefficient if friction is denoted by the symbol “U_s“. The coefficient of static friction does not have any type of units. With the help of the coefficient of static friction the force of the static friction can be calculated. The force applied by the static friction can be calculated by multiplying the coefficient of static friction with the normal force applied on the object.

The formula to find the value of static friction coefficient is given by:

Fs=µs×Fn

What is Limiting Friction?

Limiting friction is also like the Static friction. The limiting friction is also calculated between the two objects which are in static position or there is no relative motion respect to each other. With the help of limiting friction, we can find the minimum amount of force required to bring an object into motion by overcoming the limiting friction. The Limiting friction will be the maximum friction when the two objects in contact are not in motion. To find the Limiting friction when the two objects are in dry condition the equation will be normal force multiplied with coefficient of limiting friction. The limiting friction between the two objects will only come into play when one of the objects is ready to slide over the surface of the other object. The value of the Limiting friction will be the maximum value of the coefficient of static friction.

The formula to calculate the value of normal friction is:

fs=µsN

Following are the laws of the limiting friction:

The force by the limiting friction always acts in the opposite direction of the abject motion.
The Limiting force does not act in the direction of motion, and it will be always in the tangential angle.
The Limiting friction also depends on the position of the objects, and it also depends on the material of the object.
The Limiting friction does not depend on the shape of the objects.
The Limiting friction does not depend on the surface area of the objects.
The normal force and the magnitude will always be proportional to each other in any of the cases.