ABSTRACT
This chapter discusses the effect of friction on motion. The term frictional force is used to describe the force that arises when two bodies are in contact with one another and that opposes the motion of one body relative to the other. The term static friction is used when the bodies are at rest and the frictional force is opposing attempted motion; the term kinetic friction is used when the bodies are moving with respect to each other and the frictional force is opposing motion with constant velocity. The efficiency of an inclined plane can be considered to be the input work done by the force in the absence of frictional contact with the plane divided by the output work obtained by the load, the load being lifted as a result of sliding up the plane. When the load moves down the thread and overcomes the thread friction by its own weight, then it is said to overhaul.
