Chapter 8- Friction
Well you are getting down to the wire in statics and my guess is that you are pretty tired. Try to stay focused as you are almost there!
Friction shouldn't be new to you as you did study it in physics but in statics we will take it up a notch.
I will be showing you two major ways to approach friction problems. One way is similar to what we have done for most of this statics class and that is the sum of the forces, the other way is with force triangles. The difference here is you will be comparing the friction reaction to a maximum value (mu times N). If the friction force is less than that then maximum then it is in static equilibrium, if more than that then it is moving, not in static equilibrium.
The method of sum of the forces is typically used with blocks whereas the force triangle method is good for the analysis of wedges.