Lesson 5 Biomechanics
moment force lever arm M F xd
Arms VIS legs
force on arms mostly only gravity
legs also need to withstand whole body weight
muscle volume higher in legs than in arms
because internal moment needs to behigher to provide
more force
load on the leg
During standing walking the human body exerts a
or
certain force on the ground
a force on
Simultaneously the ground also exerts
the body ground reaction force
these forces have the same magnitude but have an
opposite direction action reaction 3rd law of Newton
groundreaction force
resultant force object exerts on the ground
, ground reaction force vector
magnitude
direction
point of application
Magnitude same for resultant and ground reaction force
direction is opposite not Always vertical
5
point of Application same for resultant and groundreaction force
in dynamic situation this point is not fixed
I
moment
external moment
moment caused by Ground reaction force or other external forces
internal moment
moment that is delivered by the body muscles ligaments orbones
to counteract the external moment
if both equal static situation
internal moment will Always be the opposite of the external moment
moment force lever arm M F xd
Arms VIS legs
force on arms mostly only gravity
legs also need to withstand whole body weight
muscle volume higher in legs than in arms
because internal moment needs to behigher to provide
more force
load on the leg
During standing walking the human body exerts a
or
certain force on the ground
a force on
Simultaneously the ground also exerts
the body ground reaction force
these forces have the same magnitude but have an
opposite direction action reaction 3rd law of Newton
groundreaction force
resultant force object exerts on the ground
, ground reaction force vector
magnitude
direction
point of application
Magnitude same for resultant and ground reaction force
direction is opposite not Always vertical
5
point of Application same for resultant and groundreaction force
in dynamic situation this point is not fixed
I
moment
external moment
moment caused by Ground reaction force or other external forces
internal moment
moment that is delivered by the body muscles ligaments orbones
to counteract the external moment
if both equal static situation
internal moment will Always be the opposite of the external moment
