Friction force:

$\overline{)\begin{array}{rcl}{\mathbf{f}}& {\mathbf{=}}& \mathbf{\mu}\mathbf{N}\\ {\mathbf{f}}& {\mathbf{=}}& \mathbf{\mu}\mathbf{m}\mathbf{g}\end{array}}$

Ranking based on static friction:

f_{s} = μ_{s}mg

For 1, f_{s} = (0.6)(750)(9.81) = **4415 N**

Rank the crates on the basis of the static frictional force acting on them. Rank from largest to smallest. To rank items as equivalent, overlap them. Assume the applied force is the maximum that can be applied without the crate moving.