In a laboratory experiment on friction, a 139-N block resting on a rough horizontal table is pulled by a horizontal wire. The pull gradually increases until the block begins to move and continues to increase thereafter. the figure (Figure 1) shows a graph of the friction force on this block as a function of the pull.
What would the graph look like if a 139N brick were placed on the box, and what would be the coefficients of friction be in that case?http://session.masteringphysics.com/problemAsset/1038568/5/YF-05-52.jpg

Question

In a laboratory experiment on friction, a 139-N block resting on a rough horizontal table is pulled by a horizontal wire. The pull gradually increases until the block begins to move and continues to increase thereafter. the figure (Figure 1) shows a graph of the friction force on this block as a function of the pull.
What would the graph look like if a 139N brick were placed on the box, and what would be the coefficients of friction be in that case?http://session.masteringphysics.com/problemAsset/1038568/5/YF-05-52.jpg