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Biomechanical
Principles to be Investigated
Frictional forces
Purpose
Friction is the force created by two contacting surfaces sliding past each
other. When surface A applies a frictional force to surface B, an
equal but opposite (direction) frictional force is exerted by surface B
onto surface A. How much frictional force is created between two
contacting surfaces will be determined by a) how much force is pressing
the two surfaces together (i.e., the normal or perpendicular force), b)
the type of texture covering each surface and c) the deformabillity of
each surface (Kreighbaum and Barthels, p.99). The rougher and harder
the surface textures and the greater the forces pressing the two surfaces
together, the more difficult it becomes to slide on object over the other
object. Why? This lab will investigate the ability of two
different styles of athletic footwear to generate a large coefficient of
static friction while performing a 40 yard shuttle run.
Rationale
Maximum static friction (i.e.,
resistance to initiating two contacting surfaces sliding past one another)
is desirable for sports played on grass (e.g., football, soccer, rugby,
golf). Over the past decade, therefore, athletic footwear with
cleats has evolved into several highly sport-specific designs.
Athletic footwear manufacturers alter the cleat height, shape and
composition as well as the overall tread pattern based on the linear and
or rotational sport-specific movement patterns required (Krieghbaum and
Barthels, p.101). For example, it is common for football players to
utilize multi-cleated shoes, screw-in cleated shoes and turf sneakers
during the course of one football season. Proper footwear selection
is crucial to maximize athletic performance on a given playing surface
while concurrently attempting to minimize the incidence of lower extremity
injuries.
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