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ephe 355 > kinetics > Flashcards

kinetics Flashcards

1
Q

kinematics vs kinetics

A

kinematics = describes motion w/o regard for mass/ forces
kinetics = forces that produce/ stop/ modify motion

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2
Q

5 variables that determine and describe motion:

A
  1. type
  2. location
  3. magnitude
  4. direction
  5. rate of motion or rate of change
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3
Q

2 types of motion:

A
  1. translatory/ linear = all parts travel same disrance in the same period of time in the same direction
  2. rotary = every point moves about a pivot/ axis of rotation
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4
Q

how is the magnitude of motion measured for each type?

A
  1. linear distance = meters/ feet
  2. rotary distance = degrees
    –> ROM
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5
Q

distance:

A

how far a force moves a body

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6
Q

how is location of motion described?

A

arounds axes (AP, ML, SI aka longitudinal)

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7
Q

how is direction of motion described for rotary motion?

A
  1. about medial-lateral axis = sagittal plane - flexion/extension
  2. about anterior-posterior axis = frontal plane - abduction/adduction
  3. about superior-inferior axis = transverse plane - medial/lateral rotation
    **except thumb, ankle, clavicle
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8
Q

how is direction of motion described for translatory/linear motion?

A

according to axis AND + or -

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9
Q

how can rate and change of motion be described (3)?

A
  1. velocity = rate at which motion occurs
  2. acceleration = rate at which velocity changes
  3. torque = motion occurring about an axis
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10
Q

4 types of forces that affect body motion:

A
  1. gravity - 9.81m/s^2
  2. muscles - contraction, stretching
  3. external resistance - muscles work against
  4. friction - opposes contact force, primarily responsible for human movement
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11
Q

mass vs weight

A

mass = amount of matter something contains, measured w balance comparing known matter to unknown amount of matter
weight = pull of gravity on mass (mg) measure on a scale

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12
Q

moment:

A

force acting at a distance from axis
M = d x F

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13
Q

newtons 1st law:

A

law of inertia - body at rest/motion will stay at rest/motion until acted on by external net force
sumF = 0

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14
Q

newtons 2nd law:

A

law of mass/ acceleration
F = ma

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15
Q

newtons 3rd law:

A

law of action/ reaction - for every action force there is an equal and opposite reaction force

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16
Q

3 elements of a lever:

A
  1. axis/ fixed point
  2. resistance force (R)
  3. moving/ effort force (F)
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17
Q

resistance arm:

A

perpendicular distance from axis to line of action of resistance

18
Q

force arm:

A

perpendicular distance from axis to moving force

19
Q

first class lever:

A
  • seesaw (axis b/n force and resistance arm)
    ex: C1 = skull sitting on first vertebra
  • poor mechanical advantage as muscle must generate a lot of force to overcome R
20
Q

second class lever:

A
  • wheelbarrow (axis at end, force arm > resistance arm)
    ex: achilles tendon relative to toes
  • mechanical advantage bc long F arm
21
Q

third class lever:

A
  • bicep curl w dumbbell (most common in body)
  • poor mechanical advantage = force arm is smaller than resistance arm
  • can move small weight long distance
22
Q

mechanical advantage:
equation:

A

ratio b/n length of F and R arms
MA = (force arm length)/(resistance arm length)

23
Q

what can MA ratios be?

A

> 1
<1
= 1 (no advantage, F arm length=R arm length)

24
Q

how can you increase MA?
practical example:

A

increase length of the force lever
ex: closer to person = shorter resistance arm

25
Q

torque:

A

force applied around a joint/axis
T= F x d
(so smaller moment arm, the less torque generated)

26
Q

what happens when the angle b/n forces increases?
what does it mean when angle = 0?

A

resultant force decreases
= forces are in line w eachother

27
Q

COG or COM:

A
  • point about which mass of object is balanced/ concentrated
  • a few finger widths below belly button
    ***exceptions: pregnancy, wider pelvis
28
Q

stable equilibrium

A

body returns t0 former position after light perturbation

29
Q

unstable equilibrium

A

body seeks new position after light perturbation

30
Q

neutral equilibrium

A

COG displaced but remains at same level
ex: person in wheelchair

31
Q

when in a form of equilibrium, what does the degree of stability depend on (4) ?

A
  • height of center of gravity above base of support
  • size of base of support
  • location of gravity line w/n base of support
  • body weight
32
Q

base of support (BOS):

A

when body is stable, line of gravity passes through center of BOS
larger BOS = more stable the object is

33
Q

can small changes in muscle length create angular displacements?

A

yes

34
Q

what does the amount of force a muscle must exert to overcome external resistance depend on?

A

lever arm length

35
Q

are the body’s levers designed more for speed or strength?

A

speed (most lever systems in body are third class)

36
Q

when does max resistance torque occur?

A

when segment is horizontal/ perpendicular distance to axis is greatest

37
Q

single fixed pulley:
mechanical advantage?

A
  • dont provide a mechanical advantage
  • change direction of a force
    ex: cable machine
38
Q

moveable pulley:
mechanical advantage?

A
  • provide mechanical advantage
  • pulley rope must be pulled twice the distance that weight is raised
    ex: leg traction system
39
Q

anatomical pulleys:
mechanical advantage?

A
  • change course of tendon
  • increase mechanical advantage = move tendon further from axis of rotation
    ex: patella
40
Q

leverage factor:

A
  • use principle of leverage to increase effect on an applied force; mechanical advantage = magnifies force + move object w less effort
    ex: therapist position relative to client when doing muscle testing
  • increase effective speed of movement w a given force
    ex: golf swing
41
Q

stretching vs joint mobilization:

A

stretching a joint = external forces applied distally resulting in high stresses to articular tissues
joint mobilization = external force applied proximally, recreate arthrokinematics while minimizing stress to articular tissues

ephe 355 (7 decks)

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