FINAL Flashcards

1
Q

first central difference

A

v = p/t

we plot in b/w times i.e. 5+4/2 = 4.5

however, FCD:
- use larger time frame to have an EXACT moment/velocity at a time
- still avg velocity, just larger

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2
Q

instantaneous velocity

A

no change in time, velocity at one pt in time

draw a tangent line and find when there’s a single overlap on the graph
- if tangent line somewhat flat, means there is low change in position

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3
Q

what reference system used

A

cartesian reference system

use coordinates to locate a point

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4
Q

coordinate method

A
  1. use global reference system
  2. pt P is specified
  3. location of P is found using reference system
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5
Q

how to collect data for mvmnt? veloc accel

A

use HIGH-SPEED camera, high frame rate/s

put markers on boney prominences/markings i.e. white dots

define global reference system/smth relevant to the study

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6
Q

what is linear kinematics

A

position, velocity, acc, displacement

motion: when object changes position

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7
Q

how to visually estimate velocity and acceleration

A
  1. see points of inflection
    - mins/max
    - v=0 at POI, put it on x-axis for velocity
  2. sign of slope
    - signs match, must approach zero
  3. steepness
    - if og shape is steep, velocity is STEEPER
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8
Q

shuttle run graph

A

v=0 in middle when halfway, direction change occurs
- +ve forward and -ve backward directions

even when slowing down, DIRECTION is still positive or negative
- velocity sign does not change

HOWEVER, decreasing +ve velocity means -ve acceleration (bcs ROC of v is dec)

CONCLUSIONS:
- velocity is dependent on direction
- acceleration is independent of direction, since -ve A can occur without a direction change (depends on velocity)

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9
Q

angular motion

A

body parts move thru same angle, but don’t undergo SAME linear displacement

occur about an axis of rotation

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10
Q

what is each marker called

A

proximal
vertex (middle, axis of rotation)
distal

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11
Q

relative joint angle

A

angle b/w 2 longitudinal axes of 2 segments

do NOT describe the position of the segment in space
- i.e. can be 60deg at many diff places, positions
- doesn’t say orientation

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12
Q

absolute angles

A

angle of inclination of a body segment relative to a fixed reference/horizontal i.e. ground

only needs prox and dist

DOES tell where you are in space

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13
Q

stride vs step

A

stride: heel to same heel, successive points of INITIAL CONTACT of same foot
- i.e. 2 steps
- 60% stance, 40% swing

step: heel to opp heel
- initial contact of one foot to initial contact of other foot

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14
Q

step width

A

lateral distance b/w successive points of contact of OPP feet

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15
Q

foot angle

A

angle b/w line of progression (straight line walking forward) and line b/w midpoints of calcaneus and 2nd MT head

  • at rest, angle is 0 (toes straight)
  • -ve angle is pigeon toe/anime girl stance
  • +ve angle when point outwards/elf stance
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16
Q

gait cycling time

A

allows us to see gait disorders
- analyze and track compared to baseline
- see asymmetry
- see abnormal cadence i.e. for age, sex, etc.
- improper time in double or single stance
- discover risk of falling

17
Q

cadence

A

steps/minute

18
Q

how to increase velocity i.e. walk to run

A
  1. inc stride length
  2. inc cadence (steps/min)
  3. do both

this causes stance time to dec, swing time to inc

19
Q

anatomical angle

A

relative angle is compared to angle of the joint in anatomical position (180)

20
Q

rearfoot angle

A

examining frontal plane
at rest, leg and calcaneus 90deg

uses 2 absolute angles, of leg and calcaneus

pronation:
- dorsiflexion, sag
- EVERSION, front
- abduction, hori

supination:
- plantarflex
- adduct
- INVERSION

21
Q

center of gravity

A

the point where all particles of the body are evenly distributed

22
Q

center of mass

A

point where all the body’s MASS is evenly distributed

23
Q

reaction board method

A

person lays on 2m board, with feet on fixed axis of rotation

24
Q

free body diagram

A

link b/w complexity of human situation and application of mechanic techniques

25
Q

essential feature of FBD

A

isolation of a segment

inclusion of forces working on the segment, including GRF

26
Q

steps to develop FBD

A
  1. isolate segment from rest of body
  2. identify reference system
  3. put on weight forces
    - -ve direction of segment
    - always has weight, not necessarily other forces
  4. include external/unknown forces acting on seg
  5. check forces
  6. apply equilibrium equn and solve for unknown
27
Q

assumptions of FBDs

A
  • person is static
  • all forces are acting on same 2D plane (no Z direction)
  • all joints are hinge, bcs 2D motion
  • all muscles are represented as single muscle equivalent…all are considered as primer mover
  • unknown forces acting in pos direction
28
Q

COMx equn

A

COMx = Xp + (COM/SLp)(Xd - Xp)

29
Q

COMy

A

COMy = Yp + (COM/SLp)(Yd-Yp)

30
Q

rearfoot angle equn

A

rearfoot angle = abs angle of leg - abs angle of calcaneus

31
Q

absolute angle equn

A

theta = tan(Yprox-Ydist/X prox-Xdist)