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Phys Ed > Biomechanics > Flashcards

Biomechanics Flashcards

1
Q

Newton’s 1st law of motion (inertia)

A

an object in motion or at rest will stay in motion or at rest unless acted on by an external force

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2
Q

Newton’s 2nd law of motion (acceleration/momentum)

A

force = mass x acceleration (F=ma)

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3
Q

Newton’s 3rd law of motion (action/reaction)

A

For every action there will always be an equal and opposite reaction

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4
Q

Momentum formula

A

Momentum = mass x velocity

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5
Q

what does the principle of conservation of linear momentum state? when does it occur?

A

Principle states the total momentum of two objects before and after impact are equal, this occurs in situations where a perfect elastic collision takes place (no energy is lost to sound and heat)

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6
Q

Impulse, what does it refer to?

A

Impulse = force x time and refers to the change in momentum of an object

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7
Q

coefficient of restitution (COR)

A

The ratio of relative velocity (or height) after impact to the relative velocity (or height) before collision.

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8
Q

COR formula

A

COR = square root of (height bounced divided by height dropped)

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9
Q

concentric force

A

force applied to produce linear motion e.g. hitting a float serve in volleyball

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10
Q

Eccentric force

A

off centre force applied to produce angular motion e.g. hitting a top spin serve in volleyball

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11
Q

Types of forces

A

concentric force and eccentric force

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12
Q

force that creates angular momentum (torque)

A

Caused by the application of an eccentric (off-centre) force

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13
Q

Torque

A

The magnitude of the turning force
torque = Force x Distance (T = F x D)

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14
Q

Angular momentum formula

A

Angular momentum = angular velocity x moment of inertia

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15
Q

Angular velocity

A

the velocity or speed of a rotating object

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16
Q

Moment of inertia (mass of object x radius of rotation)

A

the resistance of a rotating object to change its state of motion

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17
Q

Conservation of angular momentum

A

A spinning body will continue spinning unless an external force acts on it

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18
Q

Levers main parts

A

Weight or resistance to be moved
axis or pivot point
application of force to move the weight or resistance

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19
Q

Lever functions

A

Increase application of force by making the force arm longer than the resistance arm
increase the speed of movement by making the force arm shorter than the resistance arm

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20
Q

Fulcrum/axis

A

point around which the lever rotates

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21
Q

effort/force arm

A

the distance between the fulcrum and the point at which the force is applied

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22
Q

Resistance arm

A

the distance between the fulcrum and the centre of the resistance

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23
Q

Input (effort) force

A

Force exerted on the lever

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24
Q

Output (resistance) force

A

Force exerted by the lever

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25
Q

First class lever

A

fulcrum is located in the middle of the effort and load

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26
Q

Second class lever

A

Load (resistance) in the middle of the fulcrum and effort

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27
Q

Third class lever

A

Effort (force) in the middle of the fulcrum and load

28
Q

FLE lever acronym

A

FLE
- F - 1st class - Fulcrum in middle
- L - 2nd class - Load in middle
- E - 3rd class - Effort in middle

29
Q

ARF lever acronym

A
  • A - 1st class - Axis in middle
  • R - 2nd class - Resistance in middle
  • F - 3rd class - Force in middle
30
Q

Factors affecting use of levers

A
  • length of lever
  • inertia of lever
  • amount of force
31
Q

Length of lever affect on lever use

A

velocity is greatest at the distal end of the lever
longer lever, greater velocity at impact

32
Q

inertia of lever affect on lever use

A

longer lever = heavier lever meaning more difficult to rotate

33
Q

amount of force affect on lever

A

determines the length of the lever athlete should use

34
Q

fluid mechanics

A

the study of forces that develop when an object moves through a fluid medium (either water or air)

35
Q

fluid resistance

A

as an object moves through a fluid the fluid becomes disturbed
the greater disturbance to the fluid, the greater the transfer of energy form object to fluid

36
Q

2 factors affecting fluid resistance

A

density
viscosity

37
Q

density

A

more dense fluid results in a more disturbed fluid therefore increasing the resistance e.g. humidity

38
Q

viscosity

A

the more viscous the fluid (internal resistance of a fluid to flow), the more disturbed the fluid becomes therefore increasing resistance e.g. water is more viscous than air so a swimmer will experience more resistance than a runner

39
Q

Types of drag

A

Form drag
surface drag
wave drag

40
Q

form drag + factors affecting

A

the drag created due to a fluid moving over an object resulting in friction between the surface of the body and the fluid
- relative velocity of moving object
- relative roughness of surface object/surface friction
- viscosity of the fluid
- surface area of the object

41
Q

form drag (pressure drag) + factors affecting

A

the drag created by a pressure difference between the front and rear of an object moving through a fluid
- cross sectional area (CSA) of the object presented to the fluid
- velocity of the object
- surface roughness (surface friction)
- shape of object

42
Q

wave drag + factors affecting

A

the drag created by the body at the interface of two fluids interacting whereby waves are created
- relative velocity of wave
- technique
- open water (ocean) vs closed conditions (pool)

43
Q

boundary layer

A

Thin layer of air surrounding or attached to the ball

44
Q

Laminar

A

flow characterised by smooth parallel layer of fluid

45
Q

Turbulent

A

flow characterised by mixing of adjacent fluid layers

46
Q

boundary layer separation

A

where boundary layer breaks away from ball
earlier separation increases pressure gradient between the front and back of the ball, leading to increased drag

47
Q

Turbulent flow characteristics

A
  • high pressure at front of ball
  • late boundary layer separation
  • small turbulent pocket (high pressure) at rear of ball)
48
Q

Laminar flow characteristics

A
  • high pressure at front of ball
  • early boundary layer separation
  • large turbulent pocket (low pressure) at rear of ball
49
Q

affecting factors of boundary layer separation point

A

velocity
- low velocity results in late separation and minor drag
- high velocity results in early separation and increased drag
surface roughness
- creates turbulent boundary layer, reducing effect of drag
- e.g. dimpled vs smooth golf ball

50
Q

factors affecting drag

A

drag coefficient
cross sectional area
speed
surface roughness
mass
shape

51
Q

Drag coefficient - factors affecting drag

A
  • measurement used to quantify the drag or resistance of an object on a fluid environment
  • directly related to cross sectional area
52
Q

cross sectional area (CSA) - factors affecting drag

A
  • linear relationship exists between CSA exposed to air and drag
  • increased CSA = increased drag
53
Q

Speed - factors affecting drag

A
  • faster moving ball means earlier boundary layer separation, which means larger pressure differential between front and rear of ball therefore resulting in more drag
54
Q

Surface roughness - factors affecting drag

A
  • rough surface creates turbulent flow, therefore less drag
55
Q

Mass - factors affecting drag

A
  • greater mass of the ball means a less effect of drag
56
Q

Shape - factors affecting drag

A
  • round ball results in laminar flow oval ball results in turbulent flow
57
Q

environmental factors affecting drag

A

air density
- higher altitude results in less drag
- smaller object leads to a greater drag effect
atmospheric pressure
- increased pressure = increased density = increased drag
humidity
- increased humidity = increased density = increased drag
temperature
- increased temperature = decreased density = decreased drag

58
Q

Bernoulli’s principle

A
  • the velocity of a fluid moving over an object is inversely proportional to the pressure on the object
  • high velocity = low pressure
  • low velocity = high pressure
59
Q

Magnus effect

A
  • Term used to describe the effect of rotation on an object’s path as it moves through a fluid
  • It applies Bernoulli’s principle to explain the effect spin has on the trajectory or flight path of an object
60
Q

biomechanical principles

A

balance
coordination continuum
force-motion
force-time
inertia
optimal projection
range of motion
segmental interaction
spin

61
Q

coordination continuum - applies only to striking and throwing activities for distance

A

sequential approach to ensure maximum velocity transferred
- maximise number of body segments involved by standing side on
- sequentially accelerate each body segment
- ensure big body parts move first and small body parts move last e.g. arms to wrist
- follow through towards target to ensure safe dissipation of force

62
Q

Balance

A

the ability of something to maintain or hold its position to increase stability
- widen base of support, increase surface area with ground, lower centre of gravity

63
Q

force - motion

A

an objects motion is affected by the magnitude and direction of external forces acting on it

64
Q

force - time (impulse)

A
  • a product of the force applied to an object or body, and the duration it is applied for
65
Q

range of motion (ROM)

A

the extent or limit to which a part of the body can be moved around a joint or a fixed point, total movement joint is capable of

66
Q

Optimal projection

A
  • maximise velocity
  • maximise height of release
  • angle of release (45 degrees)
67
Q

Spin

A

Through the application of back spin to the ball, it optimises the balls time in flight (result of magnus effect), therefore maximising distance achieved.

Phys Ed (4 decks)

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