A force scale is attached to a stack of books lying on a flat table. What happens to the size of the static frictional force as you begin to pull on the force scale?

Question

anonymous · Answer

The static frictional force will remain the same. 

This frictional force is independent, in the Euler model of $F_f = F_N \mu$, of any horizontal force we apply to our mass. 

You've probably been taught that they are two types of friction; static and dynamic. We know that $\mu_s > \mu_d$which is to say that static friction is greater than dynamic friction. 

If we pull with great enough horizontal force to overcome the static friction, the books will begin to move being resisted by only dynamic friction at this point.

anonymous · Answer

thanks! also, what is the minimum size for the static frictional force, and under what conditions will the minimum static frictional force be observed?

anonymous · Answer

and what type of friction acts when the books are at rest but a force is exerted? would it be static friction?