Midterm #1 Flashcards
biomechanics
science concerned with effects of forcs in human body
topics in biomechanics
rigid body mechanics
tissue mechanics
fluid mechanics
what is the perspective of biomechanics
description of motion
cause of motion
effects of motion on musculo skeletal tissue
steps of motion analysis
description
observation
evaluation
instruction
phases of an activity description
preperation
execution
follow-through
elements of observation
best viewing angle # of viewing angles distance equipment location equipment
evaluation of an activity
identify errors evaluate errors (cause, impact, safety)
instruction
feedback
keep, stop, start
different types of planes to desxribe motion
sagittal plane
frontal plane
transverse plane
where does movement occur
inside planes and around axes
three axes around which motion occurs
mediolateral axis
anterior-posterior axis
vertical/longitudinal/superior - inferior axis
what motions occur in the sagittal plane
flexion - extension
thumb abduction adduction
foot plantar flexion and dorsiflexion
which axis is related to sagittal plane motion
mediolateral axis
what motions occure in the frontal plane
abduction - adduction
trunk and head lateral flexion
hand - ulnar and radial deviation
which axis is related to frontal plane motion
anterior-posterior axis
abduction
movement away from the midline
adduction
movement towards the midline
what motion occurs in the transverse plane?
internal - external rotation
right - left rotation
pronation - supination
what axis is related to motion in the transverse plane
logitudinal/inferion - posterior axis
internal rotation
limb rotates towards midline of body
external rotation
limb rotates towards outside of body
what motion is in the hip/coxafemoral joint possible
flexion - extension
abdution - adduction
internal - external rotation
what motion is in the knee/tibiofemoral joint available
flexion - extension
internal - external rotation (only in flexed mosition)
what motion is in the ankle/talocrural joint available
plantarflexion
dorsiflexion
what motion is in the subtalar joint available
inversion - eversion
abduction - adduction
what motion is in the Metatarsophalangeal Joints available
flexion - extention
abduction - adduction
what motion is in the interphalangeal joint available
flexion - extenion
what motion is in the shoulder/glenohumeral joint available
flexion - extension
abduction - adduction
internal - external rotation
what motion is in the elbow/humeroulnar joint available
flexion - extenion
radio - ulnar joint
pronation - supination
what motion is in the wrist/radiocarpal joint available
flexion - extension
radial deviation - ulnar deviation
what motion is in the metacarpophalangeal joint available
flexion - extension
abduction - adduction
what are motions in the vertebra
flexion - extension
lateral flexion
right - left rotation
what is circumdauction
a combination of motions
not rotation
what are dorsal and ventral
dorsal: towards the back
ventral: towards the abdomen
same as anterior and posterior for humans
what does linear kinematics describe
linear movements
what are movements in a straight line called
linear or translatory
subdivisions of translatory motion
rectilinear - motion in a straight line
curvilinear - not circles, but curved line
what is rotary motion called
angular
definition of angular motion
movement in circular manner, maintains distance around a fixed point
what kind of motion is human movement predominantly known as
joints: angular
center of gravity: curvilinear
head: linear
general motion
combination of rotary and translatory motion
how is motion described
distance
speed
acceleration
what needs to be taken into consideration when describing movement
entire body or one system
frame of reference
what does a frame of reference include
origin
direction
position (where is body located)
defintions of quantities
scalar
vector
scalar
size of magnitude only
temperature, time, weight…
vector
magnitude and direction of motion
running, throwing, swimming…
how can the distance between two points be described as
displacement
distance
measured in meters, miles, feet or yards
distance
can be a curved path
scalar quantity
displacement
shortest path between two points
vector quantity
rate of changed
how quickly a value is increasing or decreasing with time
quatity of time
scalar
what is valocity (geschwindigkeit)
vector
displacement per unit of time
what is acceleration
change in velocity over time
speeding up, slowing down or changing directions
scalar and vector
3 different types of aacceleration
positive
negative
zero
when is acceleration positive
when motion is positiv from starting point and speed increases
when motion negative from starting point and speed decreases
when is acceleration negative
slwoing down in positive direction
speeding up in negative direction
which kinematic variables are scalar
distance
speed
acceleration
which kinematic variables are verctor
displacement
velocity
acceleration
what is a projectile
an airborne body
only subjected to gravity and wind after leaving the ground
trajectory
path of a projectile
apex
highest point of a trajectory
range
horizontal displacement of a projectile
what is the velocity of a vertical throw
decreasing from bottom to apex
increases from apex to bottom
0 at apex
acceleration of a vertical throw
when ball is travelling up - acceleration -9.81
when travelling down acceleration is also -9.81
what causes acceleration in vertical direction
gravity
acceleration for a constant motion after leaving the hand
1
motion in horizontal direction is constant
realtion between motion in vertical and horizntal motion
both motions are independent of each other but form together a parabola
what determines the motion of a projectile to make the trajectory predictable
initial position/height
initial velocity
angle at takeoff
what can the angle of takeoff be used for
to predict the behavior of projectile that has a parabolic trajectory
what kind of technique is used to measure the angle of take-off
trigonometric technique
SOH, CAH. TOA
what is important regarding a max time in air for athletetic performance
large initial vertical velocity compred to horizontal
above 45 angle, ideal 90
highest vertical position
what is important regarding the minimum time in air for athletic performance
initial upward vertical velocity of ball is minimized
projection angle less than 45 somtimes less than 0 degrees
what is important regarding the peak hight of an objectt in athletic performance
max initial height
max initial vertical verlocity
angle of projection above 45
what is important regardign max horizontal displacement
max time in air
combine horizontal and vertical verlocity
angle between 0 and 90
the higher the hgiht of release, and the more air resistance upward force, the lower the projection angle can be
what is angular displacement
change in absolute angular position experienced by a rotating line
angle formed between t´final and intial postion
what is angular displacment measured with
radian theta
how do you convert degrees to radians and vis versa
degrees to radians: multiplay# of dregrres by pie/180
radians to degrees: multiply # of radians by 180/pie
what does l, r and d represent in angular and linear displacement
l: distance travelled by point of rotating object
r: radius
d: linear displacement
what is angular velocity
how fast an object changes its angular position
=angular displacement/time
expressed as radians/degrees per sec
a vector quantity
angular acceleration
rate of change of angular velocity
what is used to determine the direction of angular acceleration
right hand thumb rule
list of linear kinematics
displacement
velocity
acceleration
list of angular kinematics
displacement
velocity
acceleration
general rules regarding angular kinematics
max velocity occures mid movement
zero velocity at change of direction
max acceleration occurs to initial movement
zero acceleration at point of constant velocity (max velocity)
what is force
push or pull
can cause an object to start moving, stop, speed up, slow down, or chnage direction
comes in pairs: action - reaction
what unit is used to measure force
newton (N)
what is 1 N
force require to accelerate 1kg mass by 1M/s(square)
how much newton is 1 pound
4.448N
what rules does force follow
point of application
direction (line of action)
sense (push or pull)
magnitude
different classifications of force
internal- and external force
internal forces
act within the system
muscles, tendons, bones, cartilage
external forces
interaction with environment
contact - ground reaction force
noncontact - gravity
point of application, direction, sense, and magnitude for muscle force
muscle attachement
along fibers
pulling on distal attachement
muscle length
what is gravity
force hat pulls to objects (weight towards center of earth) towards each other
point of application, direction, sense, and magnitude for force of gravity on earth
center of mass
vertical
towards earth
depends on mass
what is normal contact force
force applied by surface on object
always perpendicular to surface
what is friction force
force resisting the motion of two solid surfaces against each other
direction of friction force
along the surface and opposite to direction of intended motion
ground reaction force
when body contacts ground, ground pushes back
applied to part that contacts ground
point of application of ground reaction force
point of contact body´s center of pressure
magnitude and direction or ground reaction force
same as force applied to ground
what is ground reaction force a resultant of
2 horzontal, 1 vertical component
can be desolved into normal contact force (vertical) + friction force (horizontal)
sense of ground reaction force
opposite to force applied to ground
tension force
pulls on body, e.g. slong a cord
force away from body
what is a free body diagram used for
describes forces acting on body
narrows used to describe forces
what is pressure
force distributed over an area
units of pressure
N/m(square)
what is torque
tendancy of a force to rotate an object about an axis, fulcrum, or pivot
moment arm
distance necessary for torque to rotate an object around a fixed axis
is perpendicular to center of rotation
examples of external torque
resistance torque
gravitational torque
examples of internal torque
motive torque
effort torque
muscular torque
external torque
force that causes rotation
applied at perpendicular distance from axis
force applied to body from outside
calculation of external torque
external force x external moment arm
calculation of internal torque
internal force x internal moment arm
internal moment arm
perpendicular distance between muscle force and joint center
when is a free body diagram in static equilibrium
when the sum of torque = 0
flexor torque = extensor torque
1st class lever
muscle force and external force on opposite sides of the center of rotation
example: neck extensors
2nd class lever
external force closer to axis than muscle force
IMA > EMA
example: standing on tip toes
3rd class lever
muscle force closer to axis than external force
IMA < EMA
example: most muscles
what is inertia
resistance of an object to any change in its state of motion
law of inertia
body remains in rest or constant linear velocity force by an external force to change state
static equilibrium
linear and rotational velocities = 0
body not moving
dynamic equilibrium
linear and rotational velocities not 0 but constant
body is moving at constant pace
relationship between inertia and mass
inertia is proportional to mass
law of acceleration
linear acceleration of body is proportional to force that causes it
inversely prportional to mass of body
what does accelerating an object result in
change in velocity
change in displacement
equation for force
force = mass x acceleration F= ma force = maxx x velocity/time
what causes the change in the momentum of a body
an impulse
impulse = momentum
(force x time = mass x velocity)
what is an impulse
force x time
force applied over a period of time
what is momentum
quantity of motion a body possesses
momentum = mass x velocity
law of reaction
for every force there is an equal and opposite directed force
according to the law of reaction when does an object speed up, slow down and is constant
speed up: when impulse that pushes forward is larger
slow down: posterior directed impulse is larger
constant: both impulses are the same
what is energy
state of matter that makes things change
scalar quantity
how can energy be conserved
can be transformed
an be transferred
kinetic energy
associated with sate of motion
0 when object is stationary
potential energy
energy a body has with potential to change something. but doesn´t currently
different types of potential energy
gravitational potential energy
strain potential energy
gravitational potential energy
potential energy a body has due to its position
strain potential energy
energy body has due to its deformation
what is work
process of changing the amount of energy in a system
scalar quantity
only occurs with a displacement
force x displacement
unit of energy and work
Joules (J)
what is positive work force
force and displacement are in same direction
energy enters system
what is negative work force
force and dispalcement are in opposite directions
energy leaving system
what does the work eneryg relationship describe
change in kinetic energy caused by a force applied of a given displacement
what is power
rate of performing work
calculation of power
average power = work/time
instantaneous linear power = force x velocity
