eli5 : Kinetic friction and Newton’s law of motion

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in high school , i solve friction questions by making FBD but recently i got a doubt while imagining a situation

suppose there is a block of mass 4kg kept on ground and we apply a force of 20N and lets assume the limiting friction is 14N and kinetic friction is 12N , so the block will start sliding and when we make equation of motion for this block we will get

20N – 12N = 4a

a = 2m/s²
so the block will have acceleration 2m/s²

but if we think of what will happen after our force, the block will stop after sometime

so what does actually happen after this 2m/s² acceleration which causes the block to stop , it will be friction obviously ( if we neglect air resistance ) but does friction keep resisting the motion of block and if yes then can anyone explain thoroughly what exactly happens cause this was never taught in our class ,
thanks

In: Physics

7 Answers

Anonymous 0 Comments

Friction is proportional to the amount of force applied. If you push on something harder or slide something heavier on the same surface, there will be more friction. Also, assuming that only friction is at play to slow it down. Then friction is decelerating the object just like the pushing was accelerating it. Its just an invisible push in the opposite directioj.

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