Chapter 4 - Biomechanics Flashcards
Sagittal
divides left and right
frontal
divides front and back
transverse
divides top and bottom
linear momentum
mass x velocity
angular momentum
inertia x angular velocity
transfer of momentum
mechanism by which momentum is transferred from one body to another
to change momentum
mechanical impulse must be applied
impulse = force x time
torque
= force x moment arm (d)
moment arm
the perpendicular distance from fulcrum to line of force action
first class lever
fulcrum between 2 forces
second class lever
resistance force between fulcrum and applied force
third class lever
applied force between fulcrum and resistance force
what kind of lever is primarily found in the body?
third-class
what is mechanical advantage?
ratio of resistance to applied force if it's 1 they are equal <1 resistance force is greater for first class, longer arm has advantage second class, applied force always third class, resistance force always
what is work?
force x distance
what is power?
work / time
or
force x velocity
what is linear kinetic energy?
.5 x mass x linear velocity squared
what is angular kinetic energy?
.5 x moment of interia x angular velocity squared
what is gravitational potential energy?
mass x acceleration x height
what is deformational energy?
energy stored in a body when deformed
how much energy in muscle activity goes toward performing mechanical work?
25%, the rest is lost to heat or recovery processes
what contributes to inefficiency?
coactivation jerky movements excessive movements isometric actions excessive centre of gravity excursions
four distinguishing muscle characteristics
excitability
contractibility
extensibility
elasticity
what is pennation angle?
angle at which fibers are arranged normally <30 degrees fusiform - straight - biceps multipennate - deltoid radiate - pecs longitudinal - abs unipennate - tibialis posterior bipennate - rectus femoris
