Friction and types of friction

MECHANICAL TIPS AND STUDY MATERIAL
Friction


The term friction is something that we use everyday even though we are unaware of it. In day to day life we have large number of situations when we experience friction. For example moving of wheels on road, writing with pen on paper, rubbing your hand against wall etc.

Its fact that when you try move a object like box, drum, goods along the ground, you will have to apply good amount of force to slide it along. In other words there is resistance offered against your force and you can only move the object when the force which you applied overcomes the resistance. This resistance is nothing but the effect of friction which is present between block and the ground.


What is friction?


When a object moves or slides over the another object their surface at the molecular level attracts each other. This  attraction of molecules creates resistance to motion of object. This resistance is called as friction.


Friction is applicable on all phases like solid, liquid and gases. 


The surface with roughness experiences larger friction force as compared to smooth surface. This is because rough surface provides more offense to motion an damps the motion.  Two rough surfaces in contact will always experience larger friction than two smoother surfaces.


But contradiction is possible, let us take a case of two absolutely smooth steel bar with no surface contaminants. When one such bar slides over other, inspite of sliding smoothly, it adheres to it. 


Types of friction


Static friction

Sliding friction

Static friction


This is applied when body is at rest. Consider a object kept on ground, at this point of time static friction is acting. When you start applying small magnitude of force, initially it will not move and object will provide resistance to your force. It will only move, once the force applied by you surpasses the frictional force.


Sliding friction


This occurs in moving or sliding bodies. As explained, the force of friction acts apposite to the motion of body and tries to damp the motion of body. Greater the roughness more will be effect of friction.


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