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Biomechanics > Exam 1: Kinematics > Flashcards

Exam 1: Kinematics Flashcards

1
Q

What is kinesiology?

A

Kinesiology: the study of art and science of human mvmt. related to sport, dance, and exercise

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2
Q

What is biomechanics?

A

Biomechanics: the scientific discipline that studies the STRUCTURE and FUNCTION of biological systems using the principles of mechanics and laws of physics

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3
Q

What is mechanics?

A

Mechanics: the branch of physics that analyzes the ACTIONS OF FORCES on particles and mechanical systems

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4
Q

What MUST be defined before determining the nature of a movment? What are some examples?

A

The mechanical systems of interest
- Usually chosen by focus of interest
- Whole body
- Segment
- Projectile

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5
Q

In biomechanics, what principles are applied when studying movement? What are the 3 concepts mentioned?

A

Math and physics principles
◦ Statics & dynamics = no change vs. change
◦ Kinematics & kinetics = descriptors vs. forces
◦ Qualitative & quantitative = aesthetics vs. numbers

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6
Q

What is static vs. dynamic?

A

Statics: (no change) branch of mechanics dealing with systems in a CONSTANT STATE OF MOTION
- a = 0
- Velocity is the same (no acceleration or set acceleration)

Dynamic: (change) branch of mechanics dealing with systems subject to ACCELERATION (a) aka change in velocity
- a ≠ 0
- a = constant
- a = variable
- velocity changes (direction, position)

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7
Q

What are the two forms of motion? Define them.

A

1) Linear motion: Motion along a line
2 types:
- Rectilinear: straight
- Curvilinear: curved
2) Angular motion: Rotation around an axis
- EX) joints

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8
Q

Is human movement linear or angular motion? What is this also called?

A

Both
General motion: combination of translation and rotation

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9
Q

Explain the motions of a football as discussed in class.

A

Angular (around internal axis of ball) and linear (trajectory of ball)

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10
Q

What are the two types of reference positions?

A
  1. Anatomical position
  2. Fundamental position
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11
Q

What is the spatial reference system? What is an example of this?

A

Spatial reference system: Used to standardize the measurements taken
- Cartesian Coordinate system (X-axis and Y-axis)
* Z-axis can be added for 3-dimensional

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12
Q

What is kinematics vs. kinetics?

A

Kinematics: Description
- Form, space and time, pattern, NO mass
Kinetics: Forces
- Cause, mass relevant
- Anthropometrics

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13
Q

What is kinematics?

A

Kinematics: the study of the description of motion including considerations of space and time

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14
Q

What is kinetics?

A

Kinetics: the study of the actions of forces

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15
Q

What is qualitative? What is quantitative?

A

Qualitative - subjective
Quantitative - numeric

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16
Q

What is anthropometrics?

A

Anthropometric: Related to the dimensions of body segments
- Segmental lengths
- Segmental weight
- Weight
- height

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17
Q

What are the two types of quantities?

A

Scalar - Magnitude (size)
Vector - Magnitude and direction

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18
Q

List the 2 different types of scalar and vector.

A

Scalar (magnitude)
- Distance
- Speed
Vector (magnitude and direction)
- Displacement
- Velocity

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19
Q

Do linear velocity and angular velocity have the same equation?

A

Yes

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20
Q

What 2 problem-solving approaches that can be used in analyzing human movement?

A
  1. Quantitative (numeric)
  2. Qualitative (subjective)
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21
Q

What are the three components of formal problems?

A
  1. A set of given information
  2. A particular goal, answer, or desired finding
  3. A set of operations or processes that can be used to arrive at the answer from the given information
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22
Q

When should you check the units of measurments?

A

If the answer is in right units

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23
Q

What is distance vs dispalcement?

A

Distance: (total ground covered) scalar quantity ; steps
Displacement: (change in position) vector quantity ; length and direction, START TO FINISH

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24
Q

What would be the displacement if an athlete starts and finish at the same spot?

A

Displacement at same place = 0

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25
Q

An athlete competes on a standard track (400m) and started and finished on the same spot. What is the distance and displacement?

A

Distance = 400m
Displacement = 0

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26
Q

What type of quantity is velocity (what must the answer include)? What is the equation for velocity?

A

Velocity is a vector (direction and magnitude)
Velocity (v) = change in position/change in time

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27
Q

What type of quantity is speed? What is the equation for speed?

A

Speed is scalar (magnitdue)
Speed = length (or distance)/change in time

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28
Q

What is acceleration (a)? Between speed and velocity, what is used to solve a? What is the equation for a?

A

Acceleration: change of velocity overtime
- Velocity is used to solve for a
- a = change in velocity/change in time

29
Q

When is acceleration zero?

A

When velocity is constant

30
Q

What type of acceleration is the following? :
a) Moving in + direction and increasing velocity
b) Moving in + direction and decreasing velocity
c) Moving in - direction and increasing velocity
d) Moving in - direction and decreasing velocity

A

a) positive acceleration
b) negative acceleration
c) negative acceleration
d) positve acceleration

31
Q

What does it mean to “resolve a vector”?

A

The answer has to have BOTH magnitude and direction (and same units)

32
Q

What is a free body diagram?

A

Free body diagram: diagram showing vector representation of all forces acting on a defined system
x-axis = air resistance and force applied to object
y-axis = weight of object

33
Q

Vector algebra:
a) What should you do with vectors going in the same direction?
b) What should you do with vectors going in opposite direction?

A

a) Add their magnitudes
b) Subtract their magnitudes

34
Q

Resultant vector/velocity

A

Product of all the other vectors
EX Q) What direction will X actually be traveling

35
Q

How do you find running speed vs running velocity?

A

running speed = stride length x stride frequency
running velocity = length/rate

36
Q

How does gait change? Describe what occurs in the beginning to the end (fatigue)?

A

a) Gait changes due to an INCREASE in speed
Beginning:
- High rate of increase of stride length
- Low rate of increase of stride frequency
End (fatigue):
- Low rate of increase of stride length
- High rate of increase of stride frequency

37
Q

(a) What is the stance to swing ratio when walking?
(b) How will this change if velocity increases?
(c) What will be the stance to swing ratio when running?

A

a) 60 to 40
b) As velocity increases, swing increase and stance decrease
c) 20 to 80

38
Q

What is the gait charateristics between men and women?

A

Men have a step length, stride length, and step width > women

39
Q

At what pace is still walking?

A

3 mph

40
Q

What equation would you use for resultant velocity?
EX ?) If a swimmer’s vleocity is 1 m/s N and the current’s velocity is 0.5 m/s E, what is the resultant velocity?

A

Pythagorean theorem
EX ?) a^2 + b^2 = c^2
(1 m/s)^2 + (0.5 m/s) ^2 = 1.25 m/s NE

41
Q

What is projectile motion and what are the horizontal and vertical components?

A

Projectile motion: Any object that leaves the ground will follow the law of physics
Horizontal & Vertical Components:
- Vertical is influenced by gravity
- No force (neglecting air resistance) affects the horizontal
- Horizontal relates to distance
- Vertical relates to maximum height achieved

42
Q

The pattern of change in the vertical velocity of a projectile is _____ about the apex.

A

symmetrical

43
Q

Vertical velocity a)_ as the ball rises and b)_ as the ball falls due to the influence of gravitational force.

A

a) decreases
b) increases

44
Q

What does gravity have a major influence on, vertical or horizontal component?

A

Vertical component

45
Q

What does apex equal to?

A

Apex = 0

46
Q

What are the three factors that influence projectile trajectory?

A

1) Angle of projection
2) Projection speed
3) Relative height of projection
~ All can be tweaked to maximize horizontal displacement

47
Q

What is the typicla projection angle that maximum horizontal range? Why?

A

45°
- Complimentary angles hit the same spot

48
Q

What does air resistance do to horizontal displacement?

A

Slows object down

49
Q

A ball is kicked off from the roof of a building having a vertical velocity of 20 m/s and horizontal velocity of 15 m/s? Answer the following questions?:
a) What is the vertical velocity at the apex?
b) What’s the horizontal vleocity without air resistance?
c) What the vertical velocity just when the ball reaches the opposite side?

A

a) Apex = 0
b) 15 m/s
c) -20 m/s (equal but opposite direction)

50
Q

What is the envelope of parabola?

A

Envelope of parabola: A given initial velocity the family of
curves that we can create by altering the angle of projection

51
Q

Optimum angle of projection

A
  • Release height = 0, then angle = 45°
  • ↑ Release height, then ↓ angle
  • ↓ Release height, then ↑ angle
52
Q

When analyzing projectile motion what is the intial velocity for the following and why:
a) Horizontal component
b) Vertical component

A

a) Horizontal acceleration = 0
- Horizontal component is constant
b) Vertical acceleration = -9.81 m/s2
- Vertical component is constantly changing

53
Q

What are the 4 equations of constant acceleration (kinematic equations)?

A

vf = vi + (a)(t)
d = vi(t) + ½(a)(t2)
Vf2 = vi2+ 2 (a)(d)
d = ((vi+ vf)/2)t

d = displacement ; v = velocity ; a = acceleration ; t = time

54
Q

Distinguish relative angles vs. absoultue angles

A

Relative angles:
- Between two segments
- Anatomical reference position
- EX: joint
Absolute angles:
- HORIZONTAL or Vertical reference
- EX: torque on spine w/ force

55
Q

What are the two tools used to measure body angles, specifically relative angles?

A

1) Goniometer
2) Electrogoniometer (elgon)

56
Q

What is used to measure body angles, specifically absolute angles?

A

1) Inclinometers

57
Q

Find the ROM with the following as if using a goniometer:
a) If starting postion (anatomical position) was at 90° and the relative joint angle is 72°, what is the ROM?
b) If starting postion (anatomical position) was at 180° and the relative joint angle is 60°, what is the ROM?

A

a) 18°
b) 120°

58
Q

Know angular quantities:
a) Pi
b) 2π
c) 1rad
d) How many revs. is a full circle?

A

a) 3.14
b) 6.28
c) 57.3°
d) 360°

59
Q

What is a radian?

A

The size of the angle subtended at the center of a circle by an arc equal in length to the radius of the circle.
- Used as a conversion factor bewteen angular and linear kinematic

60
Q

Rule of thumb between angular kinematic vs. linear kinematic equations?

A

Angular kinematic and linear kinmatic is the same equation; angular is greek vs linear is latin

61
Q

What is angular velocity and the equation? What is it measured in the units of?

A

Angular velocity: the rate of change in angular position
angular velocity = angular displacement/time
Measure in units of: degrees/s or radians/s

62
Q

What is angular acceleration and the equation? What is it measured in the units of?

A

Angular acceleration: the rate of change in angular velocity
angular acceleration = Δ ang. velocity/time

63
Q

Right-hand rule
a) Counterclockwise is
b) Clockwise is

A

a) positive
b) negative

64
Q

Angular velocities a)_ , linear velocites b)_

A

a) same
b) differ

65
Q

The ____ the radius, the LESS radial acceleration is required to make a turn

A

longer

66
Q

a) If the radius is bigger and the angular velocity is the same, is the linear velocity big or small?
b) If the radius is smaller and the angular velocity is the same, is the linear velocity big or small?

A

a) bigger
b) smaller

67
Q

What is happening to velocity if the acceleration is constant?

A

Constant acceleration = velocity is changing
- UNLESS velocity is zero

68
Q

What does angular motion mean?

A

Angular motion means there is always some ACCELERATION (radial) to change the direction of the velocity

Biomechanics (1 decks)

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