wk 3- theories Flashcards
what can force cause
motion or deformation of a mass
equation for force
F= mass x acceleration
force has what, which explains what reaction
equal and opposite reaction, explains ground reaction force
define stress
intensity of internal forces within an object or the ability to develop internal resistance to loading force
stress equation
S= force / cross sectional area
larger cross sectional area for stress means?
it can withstand higher amounts of stress and vice versa
define pressure
force applied perpendicular to unit surface area
pressure equation
P= force/area
higher pressures are caused by
smaller surface areas
define strain
relative amount of deformation of an object when it is subjected to load
the change in length
strain equation
difference in length
what is elastic deformation
initial part of strain when it can bounce back to its original length (reversible)
what is plastic defamation
second part of strain when tears occur and the material cannot go back to original length (irreversible)
exceeding what will cause rupture in material (plastic defamation)
ultimate tensile strength
what are 3 issues with roots theory
- Reliability of measurement (bisections, ROM, soft tissue movement)
- Criteria too stringent for normal foot alignment - majority have a deformity
- Position of STJ during walking