I might be asking a very elementary question here. How do we identify where static friction is acting or kinetic friction is acting?
For example, Consider this case:
Now, here we are talking about "sliding" a body along the ground with the least possible force.. If we are talking about sliding , then that would mean it will involve relative motion between the ground and the body.. causing kinetic friction. As $\mu_s$=$\mu_k$ , it does not cause much of a problem. However in the solution , it was given as follows :
When the block is about to start sliding, the frictional force acting on block reaches to its limiting valuef =$μ_s$N
Why do we not directly take the case of sliding friction here? I mean , if $\mu_s$ would not have been given equal as $\mu_k$, then why would i go with limiting case instead of directly considering the case where the object is sliding?
