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PE A-level > Biomechanics > Flashcards

Biomechanics Flashcards

1
Q

What is the definition of force?

A

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

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2
Q

What is Newtons first law?

A

A body continues in a state of rest or uniform velocity unless acted on by an external or unbalanced force

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3
Q

What is Newtons second law?

A

A bodys 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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4
Q

What is inertia?

A

The resistance of a body to change its state of motion whether at rest or while moving

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5
Q

What is veloity?

A

The rate of change in dispacement

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6
Q

What is Newtons third law of motion?

A

For every action force appiled to a body there is an equal and opposite reaction force

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7
Q

What is Newtons first law of motion also known as?

A

The law of inertia

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8
Q

What is Newtons second law of motion known as?

A

The law of acceleration

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9
Q

What is Newtons third law also known as?

A

The law of reaction

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10
Q

Sporting example: Newtons first law

A

A 100m sprinter will remain at rest in the blocks until an external force large enough to overcome the inertia creates motion

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11
Q

Sporting example: Newtons second law

A

The acceleration of a netball during a chest pass is proportional to the size of the force applied and it will move in the same direction as the force acts

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12
Q

Sporting example: Newtons third law

A

When a swimmer pushes against thw wall in a tumble turn, the wall applies a force back to the swimmer who then moves in the opposite direction of the action force

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13
Q

Velocity equation

A

Velocity=displacement/time taken

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14
Q

Momentum equation

A

Momentum=mass X velocity

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15
Q

Acceleration equation

A

Acceleration= (final velocity-intial velocity)/time taken

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16
Q

Force equation

A

Force= mass X acceleration

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17
Q

What is an internal force?

A

A force generated by the contraction of the skeletal muscles

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18
Q

Example of an intenal force being generated

A

A sprinter must contract their rectus femoris group to extend their knee and the gastrocnemius to plantar flex the ankle in order to generate the force needed to drive away from the blocks

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19
Q

What is an external force?

A

A force that comes from outside of the body and acts upon it

Ie weight, friction, reaction and air resistance

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20
Q

What are the 5 effects of force?

A
  • creates motion
  • accelerates a body
  • decelerates a body
  • changes the shape of a body
  • changes the direction of a body
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21
Q

What is net force?

A

The sum of all forces acting on a body

Resultant force

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22
Q

What happens if the netforce is equal to zero?

A

There is no chnage in motion and forces are balanced.

A body will remain at rest or continue at a constant velocity

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23
Q

What happens if a netforce is present?

A

There is a chnage in motion as forces are unbalanced.

A body will accelerate, change direction, change shape or decelerate

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24
Q

What are the vertical forces?

A

Weight and reaction

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25
Q

What are the horizontal forces?

A

Friction and air resistance

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26
Q

What is the definition of balanced forces?

A

When two forces acting on a body are equal in size and opposite in direction

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27
Q

What is the defintion of unbalanced forces?

A

When two forces are unequal in size and opposite in direction

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28
Q

What is the definition of weight?

A

The gravitational pull that the earth exerts on a body

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29
Q

Weight equation

A

Weight =ma

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30
Q

What is the defintion of reaction force?

A

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

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31
Q

What is the defintion of friction?

A

The force that opposes the motion of two surfaces in contact

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32
Q

What is the defintion of air resistance?

A

The force that opposes the motion through air

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33
Q

What factors effect friction?

A
  1. Roughness of the ground surface
  2. Roughness of the contact surface
  3. Temperature
  4. Size of the normal reaction
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34
Q

How the the roughness of the ground surface affect friction?

A

By increasing the roughness of the ground surface, friction increases

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35
Q

How the the roughness of the contact surface affect friction?

A

By increasing the roughness of the contact surface, friction increases

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36
Q

How the the temperature affect friction?

A

By increasing the temperature of the ground and contact surface, friction increases

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37
Q

How the the size of the normal reaction affect friction?

A

By increasing the size of the normal reaction, friction is increased

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38
Q

What are the factors affecting air resistance?

A
  1. Velocity
  2. Shape
  3. Frontal cross-sectional area
  4. Smoothness of surface
39
Q

How does velocity affect air resistance?

A

By increasing velocity, AR inceases

40
Q

How does shape affect air resistance?

A

The more aerodynamic the shape the lower the AR

41
Q

How does frontal cross-sectional area affect air resistance?

A

By decreasing the cross-sectional area, AR decreases

42
Q

How does the smoothness of the surface affect air resistance?

A

By increasing the smoothness of the surface, AR decreases

43
Q

What is the defintion of streamlining?

A

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

44
Q

Vertical forces example

A

When a gymnast performs a handstand reaction force is equal in size and opposite in direction to weight which acts upwards from the point of contact.
These forces are balanced and so the netforce=0 and body remains at rest

45
Q

Horizontal forces applied example

A

When sprinters run on a rubberised track their spikes generate a large frictional force from the starting blocks. Their low tucked body is clad in smooth lycra and moves relatively slowly though the drive phase which minimised air resistance. In this phase of the 100m friction exeeds air resistance. The forces are unbalanced and there is a positive netforce therefore allowing the body to accelerate forward.

46
Q

What does a free body diagram show?

A

All of the forces action on a body at a particular instant in time

47
Q

How does limb kinematics work?

A

Reflective markers are placed on the performers body and they are filmed using multiple video cameras.
The data is then transferred into the digital form for analysis.

48
Q

What are the advantages of limb kinematics?

A
  • Allows coaches to use information to change technique and improve performance.
  • Examine the effect of movements causing injury
  • Used to examine the effectiveness of a training technique
49
Q

What are the disavantages of limb kinematics?

A
  • Expensive
  • Results don’t take individual differences into account
  • Happens in a lab so game situations are hard to replicate
50
Q

Example of how limb kinematics is used

A

For example: is used when analysing a golf swing, allows the joint and limb to br analysed and evaluate for their effectiveness

51
Q

What are limb kinematics?

A

Kinematics is the geometry of the motion of objects which includes displacement, velocity and acceleration.
In simple terms, kinetics studies the forces that cause motion.

52
Q

What are force plates?

A

Force plates are platforms that measure all forces applied when a performer stands, steps across or jumps on it

53
Q

How are force plates used?

A

The platform measures the ground reaction forces that the performer generates. This can be vertical or both planes of horizontal forces. Data generated including a force time graph, power and acceleration information.
Used for sport biomechanics assessment, gait analysis, balance, rehabilitation and physical therapy.
It is a metal plate, with built in force transducers that produces an electrical output proportional to the force applied, which is displayed in graphical form on a computer.

54
Q

Sporting examples of when force plates are used?

A

Walking, running or jumping

Basketball and skating

55
Q

Whata re the advantages of force plates?

A
  1. Fast and accurate results recorded
  2. Analysis of gait, take off and landing technique
  3. Results can be used to plan training programmes
56
Q

What are the disadvantages of force plates?

A
  1. Equipment is expensive
  2. Laboratory conditions make it difficult to perform techniques (eg long jump)
  3. Limits potential use as they may adapt the way they perform due to laboratory conditions
57
Q

What are wind tunnels used for?

A

Used to analyse the amount of air resistance an object is creating whilst in motion.

58
Q

What are the advantages of using wind tunnels?

A

It allows engineers to have tight control on environmental variables such as wind speed or wind direction and gives them the ability to crontol cross winds and measure air resistance and flow with percision and accuracy in a very time efficient manner.

59
Q

What are the disadvantages on wind tunnels?

A
  1. Very expensive
  2. Rewquire complex analysis of the results by research professionals
  3. Specialised facilities usually only found at engineering bases
60
Q

Sporting example: wind tunnels

A

F1 cars are tested in wind tunnels to test the aerodynamic parts and set-ups

61
Q

What is the 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

62
Q

Where is a persons centre of mass in an anatomical position?

A

Around their naval

63
Q

Where is the centre of mass on a gymnast when performing a somersault?

A

Outside of the body to act a point of rotation

64
Q

Explain how a high jumper can move their centre of mass outside of the body to effectively perform the Fosbury flop

A

The athlete will create a j-curve in their run up to allow for a creater velocity. They will then plant their outside foot to allow their inside leg to lift, along with the arms at take-off to raise the centre of mass a high as possible. They will fully extend their spine to rotate around the bar moving the centre of mass outside their body and below the bar.
This allows the athlete to use less force to take-off but still reach the same height as previous techniques allowed and so when maximum force is generated at take-off, greater heights can be achieved.

65
Q

What is the defintion of stabilty?

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.

66
Q

What are the factors that affect stabiltiy?

A
  1. Mass of the body
  2. Height of the centre of mass
  3. Base of support
  4. Line of gravity
67
Q

How does the mass of the body affect stability?

A

The greater the mass of the body, the greater the inertia and therefor the greater the stability

68
Q

How does the height of the centre of mass affect stability?

A

The lower the centre of mass the greater the stability

69
Q

How does the base of support affect stability?

A

The greater the size of the base of support the greater the stability.
Can be moving two points of contact wider apart to create a larger surface area or increasing the number of points of contact

70
Q

How does the line of gravity affect stability?

A

The more central the line of gravity to the base of support the greater the gravity

71
Q

What is the line of gravity?

A

An imaginary line which extends from the centre of mass downwards to the floor

72
Q

How does minimising stability benifit a boxer?

A

When a boxer shifts their centre of mass, they become less stable because it causes their line of gravity to become less central. However this allows them to create more force when punching and faster movements when dodging an opponents punch.

73
Q

How does a sprinter maximise their stabilty when in the blocks?

A

Their crouched position gives them a low centre of mass.
They have a large base of support with five points of contact and their line of gravity falls within their base of support. Finally sprinters high muscle mass which increases their stability before coming out of the blocks.

74
Q

What are two functions of lever systems?

A
  1. To generate musclar effort to overcome a given load

2. To increase the speed of a given movement

75
Q

What are the compents of a lever system?

A
  • lever (bone)
  • fulcrum(joint)
  • effort(muscular force)
  • load(weight or resistance)
76
Q

What is in the middle of a first class lever system?

A

Fulcrum

77
Q

What is in the middle of a seond class lever system?

A

Load

78
Q

What is in the middle of a third class lever system?

A

Effort

79
Q

What is an example of a first class lever system? Include which each component is

A

Header in football

Effort= trapezius
Fulcrum=atlas & axis
Load= the weight of the players head

80
Q

What is an example of a second class lever system? Include which each component is

A

Long jump take off

Effort= gastrocnemius and soleus
Fulcrum= joint between the metatarsals and phalanges 
Load= the weight of the athlete
81
Q

What is an example of a third class lever system? Include which each component is

A

A bicep curl

Effort= bicep brachii
Fulcrum= elbow joint 
Load= the weight held in their hand and the weight of their forearm
82
Q

What does mechanical advantage allow?

A

A larger load to be moved with relatively small effort

Effort arm is greater than the load arm

83
Q

What lever system has mechanical advantage?

A

Second

84
Q

What is mechanical disadvantage?

A

The load arm is longer than the effort arm

85
Q

What lever system has mechanical disadvantage?

A

Third

86
Q

What does mechanical disadvantage cause?

A

It casues the performer to use a large effor to move a relatively small load.

87
Q

What are the advantages of a 1st class lever (effort closer to pivot)?

A

The load moves further than the effort

Ie. Head moves further up & down than the neck muscles contract

88
Q

What are the disadvantages of a 1st class lever (effort closer to pivot)?

A

Requires a large effort to move a smaller load

89
Q

What are the advantages of a 1st class lever (load closer to the pivot)?

A

Smaller effort will move a larger load

90
Q

What are the disadvantages of a 1st class lever (load closer to the pivot)?

A

The load moves shorter distances than the effort

91
Q

What are the advantages of a 2nd class lever?

A

Large load can be lifted with relatively little force

92
Q

What are the disadvantages of a 2nd class lever?

A

Slower movement

93
Q

What are the advantages of a 3rd class lever?

A

Fast movement-load moves further than the effort

94
Q

What are the disadvantages of a 3rd class lever?

A

Requires a large effort to move a smaller load

PE A-level (1 decks)

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