Engineering Statics

E-21


Three 4 kg packages, A, B, C are placed on a conveyor belt which is at rest. Between the belt and packages the coefficients of friction are 0.30 and 0.20 for the static and kinetic case respectively. The packages are placed on the belt so that they are in contact with each other and at rest. Determine which, if any, of the packages will move, and determine the friction forces acting on each package.

The FBD of the packages and the FBD of package C are given.  In addition 
the weights of the packages are calculated from the masses which are given.
The force equation in the y' direction is written and the normal force found.
The force equation in the x' direction is written and the frictional force found.
Since the normal force times the coefficient of friction is 11.37 which is 
more than the frictional force needed, the package C does not slide.
The FBD of package B is drawn.