23 biomechanics of the body

skeletal system includes

bone+ joints (+tissues like tendon, ligament, cartilage+ teeth)

forces acting on a system impose ___ that affect the structures of that body

loads

whether or not a system can handle these loads is dependent upon 2 things:

1. size of the force

2. area over which that force is applied

what is mechanical stress

stress= internal force (F)/ cross-sectional area of the internal surface(A)

stress=F/A

what does mechanical stress and pressure both reflect

the likelihood of injury or damage to the system

what is mechanical pressure

pressure= external force (F) / cross-sectional area of the external surface (A)

pressure= F/A

both mechanical pressure and stress are measured in

Pascals (Nm²)

a force applied to a system will place a ___ on that object

mechanical load

what defines the type of mechanical load imposed on an object

number

direction

and location of the force

what is tension/tensile stress

the resistance of an object to a force tending to tear it apart

our bones are strongest in resisting what type of stress

compression

our bones are the weakest at resisting what type of stress

shear

strain=

change in shape of a system (when force is applied?)

stress=

amount of force applied to a system

elastic behaviour=

the system stretches under load but returns when load is removed (typically when applied force is below yield point)

when does an object exhibit elastic behaviour? what does that mean?

when the applied force is below yield point

elastic behaviour= any change in shape is temporary

when does an object exhibit plastic behaviour? and what does “plastic behaviour“ imply?

when the applied force is beyond the yield point

plastic behaviour= any change in shape is permanent

describe the effect of loading as stress increases

elastic behaviour (below yield point)> plastic > breaks/fails (beyond ultimate strength)

frequency of loading looks at 2 factors:

load vs frequency of loading

the injury threshold line showed 2 things:

one force with big magnitude can cause injury/damage > acute injury

many loads of small magnitude can also cause injury/damage >chronic injury

the skeletal system is consisted of …

smooth, cardiac, skeletal muscle

__ is responsible for movement of the human body A and B system

musculoskeletal system

muscular and skeletal system

what are the components in Hill’s muscle model

parallel elastic component

series elastic component

contractile component

what does the