body is acted upon by three forces: weight W, R1 (the resultant of normal wall reaction and friction force) and R2 ( the resultant of the normal reaction of the wedge and the friction force). In the free body diagram, the resolved components of R1and R2 are shown by thin lines. If the friction angle is f, the R1and R2 will make angle with the respective normals to the surfaces. Note that coefficient of friction is givenby.
Application of Friction
Free body diagram of the weight to be lifted is shown below:
with the respective normals to the surfaces. Note that coefficient of friction 
is given by 
.