What is Friction Force? Physics

what is friction friction force our force of friction at the end of this lecture I will teach you top three exam based questions before starting the lecture click on the subscribe button and get Excel to our hundred of conceptual lectures for free firstly let me quickly revise the concept of force for example when you exert force on wheelbarrow it starts moving secondly consider that a fast golf ball is moving towards you you can stop this fast moving ball with the help of this stay now what you have learnt from these two examples and this example when you exert force on wheelbarrow motion produces an 8 thus you can say that force produces motion and stationary object secondly in this example you exert force on this fast moving ball as a result it stops thus you can also say that force stops moving objects therefore remember these two very important properties are qualities of any force I mean if you want to produce motion and an object you need to apply force secondly if you want to stop a moving object you again need to apply force now let me teach you the concept of friction let consider a football on the surface of the earth let you kick this football then you kick it you exert force on it as a result football starts moving after covering some distance it stops now listen carefully we have learned in the previous slide that it is the force that is stopping moving of Dave's here there is no one that can stop this football so we can ask this question why it stops or what is stopping it well the answer is very simple it is the earth friction a ground friction that exert force on this football and it stops I mean whenever you see moving object stops after covering some distance think that it is the ground friction that stops are slows down moving objects secondly how can friction stops this football well if the football moves in this direction the friction force adds an opposite direction friction force always resists moving objects remember that friction force is denoted by small F since it is a force therefore it is a vector quantity and it as a unit is Newton now you may be wondering that why friction exists in our daily life are what are causing it well to learn this concept you must learn these two examples let consider a smooth surface and a rough surface let you place a football on a smooth surface and on a rough surface firstly you kick this football it covers some distance and then stops due to ground friction secondly you kick this football it also covers some distance and then stops due to ground friction now here is the important question which football is covering more distance well your answer would be the football on the smooth surface covers more distance then on the rough surface are illegal or surface thus we can say that friction exists due to the roughness of ground let me repeat this important statement friction exists due to the roughness of ground larger the roughness of ground larger would be the friction force and it will therefore resist objects quickly you may be thinking that there is no roughness in this surface then why football stops Alto this surface seems very smooth but it's microscopic description reveals that still there is some sort of roughness thus remember that friction is due to the roughness of ground due to the roughness of any surface now let me teach you top-3 exam oriented questions the first question is how can we reduce friction well we can reduce friction of any surface are any ground by three simple methods firstly by polishing Fe polish the surfaces its roughness would be decreased as a result they become smooth and friction decreases secondly by applying lubricants by lubricants I mean oil are grease remember that friction of certain liquids like machine oil is less than many solids thus applying lubricants can decrease the friction of any surface thirdly by using ball bearings by this way we can convert sliding friction and to rolling friction thus we can reduce friction by polishing by applying lubricants and by using ball bearings the second question is what are the advantages of friction well there are many advantages of friction like walking and running we all work and run due to the friction between the soles of our shoes and the ground without ground friction we won't be able to work our to run secondly holding nails and world it is the frictional forces that holds the mills our scream and world thirdly lighting of a matchstick due to friction we can light a matchstick in order to burn something or to set it on fire hence remember that the advantages of friction are to walk or to run holding nails and wood and lighting of m-max take the last question is that what are the disadvantages of friction sometime friction can be a hindrance for example stops are slows down moving objects for instance it slows down moving vehicles are completely stops them secondly energy wastage due to friction and machineries to overcome friction a large sum of energy is vested due to which cost of production increases thirdly produce wear and tear it means due to friction many parts of a system are any machine damages with the passage of the time due to friction does the disadvantages of friction are slows moving objects energy wastage due to friction and produce wear and tear remember that there are different types of friction like static friction kinetic friction sliding friction and rolling friction which I will discuss in my upcoming videos this was all about friction exam oriented questions if you have learned something new in this video they like this video and subscribe our channel for more conceptual lectures thank you very much for watching this video

Channel: Najam Academy

Views: 53,078

Keywords: friction examples, advantages of friction, disadvantages of friction, types of friction, laws of friction, physics, force of friction, najam academy

Id: r9FMinJDq-M

Length: 9min 6sec (546 seconds)

Published: Mon Apr 20 2020