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Pe A-level HK > Biomechanics > Flashcards

Biomechanics Flashcards

3.1 principles - newton and 3.2 stability and lever systems

1
Q

What is Biomechanics?

A

Study of human movement and the effect of force and motion on sports performance

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2
Q

How does the laws and principles enables performers and coaches

A

Analyse performance
maximise perfomance
reduce or prevent injuries
design equipment

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3
Q

What is Newton’s first laws of motion?

A

Law of Inertia-
A body continues in a state of rest or uniform velocity unless acted upon by an external or unbalanced

Eg- the greater the mass of the sprinter the greater the force needed to accelerate away from the blocks.

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4
Q

What is inertia-

A

The resistance of a body to change its state of motion

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5
Q

Apply Newtons first law of motion for a 100m sprinter?

A

The 100m sprinter will remain at rest in the blocks until an external force large enough to overcome their inertia creates motion.
Equally when the sprinter reaches constant velocity, they should continue at that constant velocity until an external or unbalanced force acts upon them to change.

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6
Q

What is velocity

A

The rate of change in displacement. This is a term used throughout this chapter and although closely related to speed, includes a directional element

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7
Q

What is Newton’s second law of motion?

A

law of acceleration-
“A body’s rate of change in momentum is proportional to the size of the force applied and acts in the same direction as the force applied”

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8
Q

Apply newtons second law

A

The greater the force applied to the sprinter the greater the rate of change in momentum and therefore acceleration away from the blocks. The force is applied in a forward direction so the sprinter drives towards the line.

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9
Q

What is momentum

A

the quantity of motion possessed by a moving body

Momentum (kgm/s) = Mass X velocity

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10
Q

What is acceleration?

A

The rate of change in velocity.

Acceleration (m/s/s) = (Final velocity - initial velocity) / time

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11
Q

What is newtons third law of motion

A

law of reaction

“For every action force applied to a body there is an equal and opposite reaction force”

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12
Q

Apply newtons third law

A

when the 100m sprinter applies a down and backward action force into the blocks, the blocks provide an equal and opposite up and forward reaction force to the sprinter to rive them out the blocks

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13
Q

Calculation for velocity

A

Displacement m / time taken s
(m/s)

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14
Q

Calculation for momentum

A

mass x velocity
(kgm/s)

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15
Q

Calculation for acceleration

A

(Final velocity- inital) / time taken
(m/s/s)

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16
Q

What is force

A

A push or a pull that alters the state of motion of a body

Internal force generated by the contraction of skeletal muscle

External force comes from outside the body and acts upon it.

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17
Q

calculation of force

A

Mass x acceleration
measured in newtons (N)

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18
Q

What are the 5 effects force can have?

A

1- Can create motion
2- Can accelerate a body
3- Can decelerate a body
4- Can change the direction of a body
5- Can change the shape of a body

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19
Q

using a football penalty- explain how force affects it

A

1- The football will remain at rest on the penalty sport until a force is applied
2- The greater the force applied by the footballers foot to the ball, the greater the rate of acceleration towards the goal.
3- the ball moves through the air towards the goal, the force of air resistance will act in the opposite direction and slow it down
4- as the goalkeeper dives to save a high corner shot, he will apply a force from his hands to the ball, changing its direction pushing it way from goal
5- if the goalkeeper fails to make the save, the force of the ball coming into contact with the net will make the net change shape

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20
Q

What is net force?

A

The sum of all forces acting on a body. (also known as resultant force)

If a net force is present, there is a change in motion as the forces are unbalanced

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21
Q

What are horizontal and vertical forces in netforce

A

the vertical that push a body up and pull a body down and
the horizontal forces that push a body forwards and pull it backwards

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22
Q

What are balanced forces

A

These occur when two or more forces acting on a body are equal in size and opposite in direction.

Net force = 0, the body will remain at rest or in motion with constant velocity

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23
Q

What are unbalanced forces

A

These occur when two forces are unequal in size and opposite in direction.

A net force will be present and the body will change its state of motion, either accelerating or decelerating

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24
Q

What are the vertical forces

A

weight and reaction

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25
Q

What is weight

A

gravitational pull that earth exerts on a body and is measured in newtons

weight is always present and acts downwards from the body’s centre of mass.

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26
Q

calculation of weight

A

mass x acceleration due to gravity
(N)

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27
Q

What is Reaction

A

Is the equal and opposite force exerted by a body in response to the action force placed upon it

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28
Q

What is reaction measured in

A

Newtons

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29
Q

What are the Horizontal Forces

A

Friction and Air resistance

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30
Q

What is friction

A

The force that opposes the motion of two surfaces in contact

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31
Q

What is Friction measured in?

A

Newtons

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32
Q

What factors affect friction?

A

Roughness of ground surface
Roughness of contact surface
Temperature
Size of normal reaction

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33
Q

How does the roughness of the ground surface affect friction?

A

Increased roughness = Increased friction

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34
Q

How does the roughness of the contact surface affect friction?

A

Increased roughness = friction increased

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35
Q

How does temperature affect friction?

A

Increased temp of ground and contact surface = friction increased

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36
Q

How does increasing the size of normal reaction affect friction?

A

Increasing size of normal reaction = increased friction

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37
Q

What is air resistance?

A

A force that opposes the motion of a body traveling through the air

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38
Q

What is air resistance measured in?

A

Newtons

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39
Q

What factors is air resistance affected by?

A

Velocity
shape
Frontal-cross sectional area
Smoothness of surface

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40
Q

How does velocity affect air resistance

A

Increasing velocity= increased air resistance

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41
Q

How does shape effect air resistance

A

More aerodynamic the shape = lower air resistance

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42
Q

How does frontal cross-sectional area affect air resistance?

A

decreasing frontal cross-sectional area= decrease air resistance

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43
Q

How does smoothness of surface affect air resistance?

A

Increasing smoothness = air resistance decrease

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44
Q

What is streamlining?

A

The creation of smooth air flow around an aerodynamic shape to minimise air resistance

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45
Q

What is a free body diagram?

A

A clearly labelled sketch showing all of the force acting on a body at a particular instant in time

46
Q

What is the origin and direction of the arrow for weight in a free body diagram

A

From the centre of mass - downwards vertically

47
Q

What is the origin and direction of the arrow for reaction in a free body diagram?

A

From the point of contact extending vertically upwards

48
Q

What is the size of the arrow and relationship between weight?

A

If weight is equal in size to reaction (W=R), net force is zero.
Forces are balanced (equal in size and opposite in direction)

Therefore, the body will remain at rest.

49
Q

What is the size of the arrow and relationship between weight?

A

If reaction force is greater than weight (R>W), net force is positive.
Forces are unbalanced and acceleration in an upward direction will occur.

50
Q

Origin and direction of arrow of friction?

A

From the point of contact and usually extending horizontally in the same direction as motion (parallel to the surfaces)

51
Q

What are the components of a lever

A

Fulcrum
Load
Effort

52
Q

What are levers

A

important in understanding how the body moves

53
Q

What is the fulcrum

A

The pivot point eg a joint

54
Q

What is the load

A

The resistance or weight being moved (eg body weight)

55
Q

What is the effort?

A

The force applied (eg muscle contraction

56
Q

What is a first class lever

A

The fulcrum is between the load and the effort (eg neck extension - header in football)

57
Q

What is the mechanical advantage of first-class levers

A

If the effort arm is longer than the load arm (less effort to move a large load

58
Q

What is the mechanical disadvantage of first class levers

A

if load arm is longer- more effort to lift a smaller load

59
Q

What is a second class lever

A

The load is between the effort and the fulcrum (eg calf raises- ball of foot is fulcrum

Move large load with little effort

60
Q

Are second class levers a mechanical advantage or disadvantage

A

Always advtanage

61
Q

What is a third class lever

A

The effort is between the load and the fulcrum (most movements in the body)

Greater range of motion and speed

62
Q

Are second class levers a mechanical advantage or disadvantage

A

Always disadvantage

63
Q

What is linear motion

A

Movement in a straight line

64
Q

What is distance

A

The total path traveled by a body

65
Q

What is displacement

A

The shortest straight line distance between the start and finish points

66
Q

What is speed

A

The rate at which an object covers distance
speed = distance / time

67
Q

What is velocity

A

The rate of change of displacement

velocity= displacement/ time

68
Q

What is acceleration

A

The rate at which velocitu changes

acceleration = change in velocity / time

69
Q

What is momentum

A

The quantity of motion possessed by a moving body
momentum = mass x velocity

70
Q

Calculation of weight

A

mass x gravitational field strength (m x g)

71
Q

calculation of velocity

A

displacement / time

72
Q

Definition of centre of mass

A

the point at which a body is balanced in all directions, the point from which weight appears to act

73
Q
A
74
Q

Factors affecting position of centre of mass

A

shape of body and
distribution of mass

75
Q

What is stability?

A

The ability of a body to resist motion and remain at rest, or for a body to withstand a force applied and return to its original position without damage

76
Q

4 factors that affect stability

A

1- mass of body
2- height of centre of mass
3- base of support
4-line of gravity

77
Q

What are the 3 technological methods to analyse biomechanics

A

1- limb kinematics
2- force plates
3- wind tunnels

78
Q

What is limb kinematics

A

Study of movement in relation to time and space

Used to film and study movement

Can help improve technique

79
Q

What are force plates

A

A rectangular metal plate with built in transducers usually sunk into the ground

Measure ground reaction force
can be used for gait analysis

80
Q

What are wind tunnels

A

controlled spaces for testing airflow over objects

Test aerodynamics

81
Q

4 components of a lever system

A

lever,
fulcrum,
effort,
load

82
Q

What is the effort arm

A

distance from effort to fulcrum

83
Q

What is the load arm

A

the distance from the load to the fulcrum

84
Q

What is a first class lever

A

fulcrum is in the middle

85
Q

2nd class lever

A

load in the middle

86
Q

3rd class lever

A

effort in the middle

87
Q

Mechanical advantage of 2nd class lever

A

when the effort arm is greater than the load arm —— a large load can be moved with a relatively small effort

88
Q

Mechanical disadvantage of a 3rd class lever

A

when the load arm is greater than the effort arm—— a large effort is required to move a relatively small load

89
Q

What is eccentric force

A

A force applied outside the centre of mass, resulting in angular motion

90
Q

What is torque

A

a measure of the turning force applied to a body

91
Q

What is angular velocity
and formula

A

the rate of change in angular displacement

angular displacement / time taken
=radians per second(rad/s)

92
Q

What is angular distance?

A

total angle of a body turns from start to finish when rotating about an axis

93
Q

What is angular displacement

A

the smallest angle between the start and finish position of a body rotating about an axis

94
Q

What is angular speed and formula

A

the rate of change angular distance

angular distance/ time taken
= radians per second

95
Q

Angular acceleration/ deceleration definition and formula

A

The rate of change in angular velocity

(Final angualr velocity - initial angular velocity)
/
time taken

96
Q

What is moment of inertia

A

The resistance of body to change its state of angular motion or rotation

97
Q

What is an internal force

A

generated by the CONTRACTION of SKELETAL MUSCLE

98
Q

Examples of internal force

A

100m- contract rectus femoris - extend
knee- drive away from blocks

99
Q

What are 4 examples of EXTERNAL FORCES

A

WEIGHT
REACTION
FRICTION
AIR RESISTANCE

100
Q

5 effects of FORCE

A

Create motion
accelerate
decelerate the body
changing the direction
changing the shape

101
Q

What is limb kinematics

A

the study of movement in relation to time and space

3D or optical motion analysis records an athlete performing a sporting action.

102
Q

Force plates

A

Ground reaction forces can be measured in laboratory conditions using force plates

Data from an athlete balancing, running or jumping on a force plate and can be used to assess the size and direction

103
Q

What is reliability?

A

To extent to which an experiment, test or measuring procedure gives the same results after repeated trials

104
Q

What is validity?

A

how well a test measures what it claims to measure

It is important for a test to be valid in order for the results to be accurately applied and interpreted

105
Q

Negative of biomechanics tests

A

specialist, expensive and usually in a lab

106
Q

What are wind tunnels

A

F1 teams spend tens of millions getting the aerodynamics of the car right

Can even use for cycle helmet

object placed inside the wind tunnel- may study the flow of air around an object

aim of wind tunnel is to improve the flow of air around an object- streamlining its path through the oncoming air and potentially increasing lift or decreasing drag

107
Q

Negatives of wind tunnnels

A

Need specialist faciloties- housed in engineering bases

very expensive and require complex analysis

108
Q

What is the fosbury flop technique

A

-uses a j-curve to allow greater velocity

-plants the outside foot to allow the inside leg to lift, along with the arms, at take off to raise the centre of mass as high as possible

-fully extends the spine to rotate around the bar moving the centre of mass outside the body and below the bar.

fosbury flop technique requires less force at take-off to clear the same heights as earlier techniques.

109
Q

What are lever systems

A

the co-ordination of our bones and muscles, primarily to create human movement

110
Q

functions of lever systems

A

to generate musclaar effort to overcome a given load
to increase the speed of a given movement3`

Pe A-level HK (6 decks)

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