The effects of third-order torque and self - Saint Louis University

etween the objects is expressed as two components when
there is attempted or actual relative displacement between
surfaces in contact. One component, the normal force, is a
pushing force with an orientation perpendicular to the
shared contact-surface. The frictional force component
impedes the motion between the surfaces and is, therefore,
opposite in direction to that of intended or actual motion. 5
The maximum static or the kinetic frictional force (F)
tangent to the two surfaces is often hypothesized as
proportional to the normal force, as expressed by the
equation F = µN, where µ is the coefficient of friction
between the surfaces, and N is the normal-force magnitude
against the contact-surface of the object to be displaced. 6
Each of two coefficients of friction is a constant which is
related to characteristics of the contacting surfaces of
the objects; they are known as the static and kinetic
coefficients of friction. 7 Ordinarily in static situations,
the frictional force is just large enough to prevent
relative tangential movement. Maximum static friction
refers to the resistance to displacement encountered at the
onset of motion; it corresponds to the smallest action
required to initiate motion between surfaces that are at
rest. Kinetic friction is the frictional force that
impedes displacement during sliding motion between the
4