Simple Behavioral Aspects of Static and Kinetic Friction

SIMPLE BEHAVIORAL ASPECTS OF STATIC AND KINETIC FRICTION 

AS pointed out above, the arrangement depicted in Fig. 7-3 can be used as a simple apparatus for carrying out a friction experiment. Let us examine how it is used to investigate the behavior associated with static and kinetic friction. Consider the behavior of the block as shown in Fig. 7-5a. The normal force N is equal to W and the friction force is 

The elastic compliance of the apparatus is discussed in detail in Chapter 8, Section 5. 

In terms of the behavior that actually would be observed with a simple apparatus of the kind described above, there is a direct and obvious phenomenological difference between static and kinetic friction. Close inquiry has revealed that in addition to theoretical considerations, the experimental methods and the instrumentation used to study and measure friction are an important aspect of the behavioristic manifestation of this difference. Therefore an examination of some-7 of the more refined methods for the investigation of friction is in order. 

The American Society of Lubrication Engineers has issued a compilation of friction and wear devices [2] which describes 234 different pieces of apparatus. However, the measurement of friction is governed by only a few basic principles, and consequently an appreciation of the practical techniques employed is not difficult to acquire. To quote Bowden and Tabor [3] Any method which will give at the same time a measure of the normal load between surfaces and of the tangential force necessary to cause sliding can be used to determine the coefficient of friction.  

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