# Question about inertia

Tags: inertia
 PF Gold P: 1,516 The Coin(Green) in lying on a paper which is lying on a box.When I pull the paper with a higher force so that I could remove it easily,the coins stays about the same place. When I remove the paper slowly,the coin comes with the paper. Why? I think that objects can react(Move) to smaller forces easily but for larger forces,it doesn't. What do you think? Attached Thumbnails
Mentor
P: 17,556
 Quote by adjacent Why?
Because the coefficient of static friction is higher than the coefficient of kinetic friction.

 Quote by adjacent I think that objects can react(Move) to smaller forces easily but for larger forces,it doesn't. What do you think?
No, that is wrong.
PF Gold
P: 1,516
 Quote by DaleSpam Because the coefficient of static friction is higher than the coefficient of kinetic friction.
What?I don't Understand

 P: 999 Question about inertia In addition to the difference between static and kinetic friction, there is the difference between fast and slow. If you pull the paper with high force, you pull it fast. There is not much time for the coin to speed up. If you pull the paper with low force, you pull it slow. There is more time for the coin to speed up. The momentum delivered by a fixed force over a time interval is proportional to the duration of that interval.
 Mentor P: 17,556 Static friction force is given by $f_s\le\mu_s N$ and kinetic friction force is given by $f_k=\mu_k N$. In both cases N (the normal force) is the same, so ##f_s## (the friction force without slipping) can be larger than ##f_k## (the friction force with slipping).
 PF Gold P: 1,516 Oh .Now I Understood.Thanks

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