21 terms

kinetics

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Terms in this set (...)

Stress
Force per unit area that develops on the cross section of a structure in response to externally applied loads
Yield point
where permanent deformity occurs when load exceeds ability material to return to original shape
Plasticity
Material tolerates deformation after the yield point (before failure)
Failure point
failure of material
Stiffness
Resistance offered by tissue or material as it deforms from an external force
Strain
deformation that develops within a structure in response to externally applied force
Strain
change in length, change in structure due to a force
Elasticity
Ability to return to original shape after removal of load
Hysteresis
Work done to deform is greater than that of the material returning to original shape;
Creep
Increase in strain over time with a constant load (no change in stress)
Viscoelasticity
attributes of solid & fluid; characteristics of elasticity and viscosity
Viscous
resist loads producing shear
Macrotrauma
an acute stress (loading) that occurs when a single force is large enough to cause injury of biological tissues
Microtrauma
a repetitive stress that in of itself is insufficient to damage the tissue, causes injury when repeated over a period of time
Concurrent
Action lines will meet at a point or if extended will meet at a point
first class lever
To forces and an axis of rotation is in the middl
second class lever
fulcrum or axis is at the end of the lever, resistance is in the middle, applied force at the opposite end. example = wheelbarrow
third class lever
Lever in which the effort is in the middle of the resistance and the fulcrum; the effort travels a shorter distance and always must be greater than the resistance; example is the forearm with the elbow is the fulcrum, the effort is applied by the biceps muscle, and the resistance is the load (dumbbell)
moment arm
Distance is the moment arm ( the perpendicular distance between the line of force and the axis of rotation
torque
Ability of a force to turn a lever or cause rotation
Force has no moment ________
it is then all linear; no torque or rotary component