Chapter 3 Flashcards
Kinetic Concepts of Human Movement (70 cards)
1
Q
Biomechanics
A
The study of living things from a mechanical perspective.
Using principles of physics (motions and forces) to refine movement.
2
Q
Quantitative Analysis
A
The analysis based on measurements involving kinematic (distance) and kinetic (force)
3
Q
Qualitative Analysis
A
The analysis based off specific feedback
4
Q
When planning a biomechanical analysis, coaches need to…
A
- Identify the question of interest
- Determine how they should observe a performance
- Have the learner repeat the task over and over to ensure a good observation
- Consider external factors; clothing, setting, visability
- Decide if it is to be recorded visually or digitally
- Consider characteristics of the performer; age, gender, anthropometry (characteristics of someone’s body)
5
Q
How can biomechanics be recorded?
A
Light gates Timers Digital recorders Video analysis Optoelectronic motion analysers Goniometry Accelerometers Electromyography Apps
6
Q
Video analysis
A
- Video footage
- Can be qualitative or quantitative
7
Q
Optoelectronic Motion Analysis
A
Uses cameras that project infrared light onto reflective spheres, called targets, placed on the body. The targets reflect an ‘image’ that can be captured by the camera, transmitted to a computer as digital information, and analysed.
8
Q
Goniometry
A
Is the measurement of joint angles (in a static position)
9
Q
Accelerometers
A
Measures the acceleration of the body
eg pedometers
10
Q
Light gates and timers
A
Measure speed and velocity
11
Q
Force Platforms
A
- Embedded in running tracks, laboratory floors and diving platforms
- Measure ground reaction force
12
Q
Electromyography
A
Records the electrical activity within a muscle just contraction
13
Q
Apps
A
Perform movement analysis
14
Q
Force
A
Interaction between two objects and defined as a push or pull
15
Q
Forces can affect objects in two ways:
A
- Changing the shape of an object (squashing, twisting, stretching)
- Move the object (speed up, slow down, change direction)
16
Q
Why can you not see the reaction between the ground and your feet when you walk?
A
Because the ground is so large!
17
Q
Force(N)=
A
Mass (kg) x Acceleration (m/s)
18
Q
Mass
A
A measure of the amount of matter an object is made up of. Not weight!
19
Q
Acceleration
A
Change in velocity in a given period
20
Q
Weight
A
Is a force that is exerted on the body by gravity.
21
Q
Weight(N)=
A
Mass (kg) x Gravity (m/s)
22
Q
Friction
A
- Occurs when two surfaces come into contact with each other
- Increased and decreased friction can both be beneficial
23
Q
Maximum Static Friction
A
The maximum amount of friction that can be generated between two unmoving objects
24
Q
What specific substances/objects decrease friction?
A
Fluids eg water, oil, synovial fluid in the body
25
Drag Forces
The force that is generated when an object or body moves through air/water/other gas or fluid
26
How do athletes maximise speed?
Athletes aim to minimise the impact of friction, frontal resistance and drag
27
What is the amount of drag affected by?
Air-density, cross-sectional area of the body and speed in which the object is travelling at
28
The greater the speed, the ............. the drag force
Greater
29
Gravitational Forces
The force of attraction between two bodies or objects
30
Give an example of gravitational forces on earth
It is the force that pulls objects towards the ground, towards the centre of the earth eg gravity
31
Inertia
The tendency for a body or object to resist a change in motion
The size of inertia an object has is directly related to the mass of the object. Thus, the larger the mass, the larger the inertia, the harder it is to move or change the direction of the object
32
Is it harder or easier to change the state of motion of an object that has greater inertia?
Harder
33
Explain inertia relating to the human body
In the human body, our muscles enable us to oversome inertia by providing the force to start/stop motion, accelerate/decelerate and even change direction
34
Momentum
Is the measure of the amount of motion an object has and its resistance to changing that motion.
35
Momentum=
Mass (kg) x velocity (m/s)
36
What momentum would an object have if it was not moving and why?
Zero momentum as it has no velocity
| Momentum=massx0=0
37
In relation to momentum, what happens if two objects of the same mass but different velocities collide?
The object with the greater velocity will have the greater momentum.
38
In relation to momentum, what happens if two objects of the same velocity but different mass collide?
The object with the greater mass will have the greater momentum.
39
Are objects with greater momentum harder or easier to stop?
Harder
40
A change of momentum:
A change of an object's velocity
41
When players/objects collide,
they will continue to move in the same direction of the greatest momentum
42
Conservation of Momentum
The momentum before the collision (calculated by adding the momentum of both objects) will equal the momentum after the collision
Not including any external factors eg friction, air resistance
43
Conservation of Momentum=
```
M x v + m x 0 = M x 0 + m x V
Therefore, Mv=mV
M= mass of object 1
m= mass of object 2
v=velocity of object 1
V= velocity of object 2
```
44
Summation of Momentum
By coordinating all body parts, the momentum of each part can be added up to generate maximum velocity.
Requires multiple joints eg legs, hips, shoulders, elbows, hands etc
45
What else is Summation of Momentum referred to as?
Summation of forces/speed
| Kinetic Link Principle
46
How is maximum velocity achieved?
From momentum being generated in a sequential manner, from the body parts closest to the centre of gravity to those further away.
47
Example of momentum being generated in a sequential manner...
In throwing: The momentum generated in the lower body is transferred to the hips and trunk, then to the shoulders and elbow, and finally to the wrist
48
Impulse
Is defined as the change of momentum of an object
49
Impulse=
Force (N) x Time (secs)
50
How does momentum change?
A force must be applied to an object for a period of time
51
How can sport impulse be manipulated to increase/decrease velocity?
- Applying a small force for a large period of time
| - Applying a large force for a small period of time
52
How can manipulating impulse result in a less chance of injury?
Increasing the time in which the force is applied decreases the impact of the force, preventing injury.
53
Newton's First Law of Motion
Law of inertia
| "a body will remain at rest or in uniform motion in a straight line unless acted upon by an external force"
54
Give an example of newton's first law of motion
A soccer ball won't move from the position it has been placed in until a player applies a force by kicking it.
55
Newton's Second Law of Motion
Law of acceleration
"A force applied to an object will produce a change in motion (acceleration) in the direction of the applied force that is directly proportional to the size of the force"
56
Give an example of newton's second law of motion
The acceleration of a soccer ball depends on the force applied
57
Newton's Third Law of Motion
Law of Action-Reaction
| "For every action there is an equal and opposite reaction"
58
Explain Newton's Third Law of Motion
When two objects come into contact with one another, they exert forces that are equal in size but opposite in direction on each other.
59
Newton's First Law of Angular Motion
The angular momentum of a body remains constant unless acted upon by an external torque.
60
Torque
A force that tends to cause rotation around the object's own axis.
61
Newton's Second Law of Angular Motion
A torque applied to an object will produce a change in angular motion in the direction of the applied torque that is directly proportional to the size of the torque and inversely proportional to the moment of inertia of the object.
62
Newton's Third Law of Angular Motion
For every torque there is an equal and opposite torque.
63
Angular Momentum
The amount of angular motion possessed by a body. It is is the product of the moment of inertia and the angular velocity of an object rotating around an axis.
64
Moment of Inertia=
Mass x radius^2
| distribution of mass-kgs x the axis in which a body rotates
65
Angular Momentum=
Moment of Inertia x Angular Velocity
| reluctance to rotate x speed of rotation
66
Explain moment of inertia relating to the mass and axis of an object...
The closer the mass is to the axis, the lower the moment of inertia is and vice vera. The greater the mass, the higher the MOI.
67
Is it harder or easier to rotate if the mass of an object is closer to the axis?
easier
68
Why is junior sporting equipment made smaller?
Because the mass is closer to the axis (body) allowing the rotation to be easier
69
Angular Momentum - Conserved
If angular momentum is conserved and the mass of the object is unchanging, an inverse relationship between the moment of inertia and angular velocity occurs involving the radius of rotation.
70
If the radius of rotation is decreased,
the MOI is decreased and the angular velocity increases eg a gymnast somersaulting and vice versa; a diver coming out of a tuck
