3.2.2 - Biomechanical movement Flashcards
Biomechanical principles, levers, linear motion, angular motion, projectile motion, fluid mechanics (complete) (110 cards)
1
Q
Describe Newton’s first law
A
Every object will remain at rest or in uniform motion in a straight line unless compelled to change it’s state by the action of an external force. This is taken as the definition of Inertia. (Law of inertia)
2
Q
Describe Newton’s second law
A
The velocity of an object changes when it is subjected to an external force. Acceleration - F=MA (Law of acceleration)
3
Q
Describe Newton’s third law
A
For every action there is an equal and opposite reaction -
ground reaction force (Law of action/reaction)
4
Q
Define Linear motion
A
Motion in a straight or curved line, with all body parts moving the same distance at the same speed in the same direction.
5
Q
Define Scalar
A
Numerical value, has a magnitude but no direction.
6
Q
Give examples of Scalar quantities
A
mass, speed, distance
7
Q
Define Vector
A
Has magnitude and direction
8
Q
Give examples of Vector quantities
A
weight, acceleration, displacement, velocity, momentum
9
Q
Define Speed
A
The rate of change of position
10
Q
Define Stability
A
The ability to be able to maintain the centre of mass
11
Q
What 5 factors determine Stability
A
- size of base of support
- height of centre of gravity above base of support
- location of the centre of gravity projection within the base of support
- body mass or body weight
- friction
12
Q
Give factors for high Stability (low mobility)
A
- large base of support
- low centre of gravity
- large body mass
- high friction
13
Q
Give factors for low Stability (high mobility)
A
- small base of support
- high centre of gravity
- small body mass
- low friction
14
Q
Define fulcrum
A
The pivot/point of movement (in the body this would be a joint)
15
Q
Define load
A
The load to be moved (usually a weight)
16
Q
Define effort
A
The force applied to move the object (in the body, this will be a muscular contraction)
17
Q
What is the equation for mechanical advantage?
A
effort arm / resistance arm
18
Q
What are the mechanical advantages/disadvantages of a third class lever?
A
- Large range of movement
- Load can be moved quickly
- Large effort needed to lift relatively small load
19
Q
What are the mechanical advantages/disadvantages of a second class lever?
A
- Can lift a large load with relatively little effort
- Slow movement
- Limited range of movement
20
Q
What is the difference between mass and weight?
A
Mass is how much you weigh and weight is how much you weigh depending on gravity
21
Q
What is mass measured in?
A
kg
22
Q
What is weight measured in?
A
Newtons (N)
23
Q
What is the equation for weight?
A
mass x gravitational field strength
24
Q
What is your weight on the moon?
A
1/6 of your weight on earth
25
What is gravity on earth?
9.8
26
Define speed
The the rate at which something passes a point
27
Define distance
The path a body takes as it moves from the starting to finishing position (measured in m)
28
Define displacement
Shortest route in a straight line between the starting and finishing position (measured in m)
29
What is the equation for speed?
distance covered / time taken (m/s)
30
What is the equation for Velocity?
displacement / time taken (m/s)
31
Define velocity
the rate of change of displacement
32
Give the equation for average acceleration.
change in velocity / time (m/s2)
33
Equation for change in velocity?
Final velocity - initial velocity
34
Equation for momentum?
mass x velocity (kgm/s)
35
What is an internal force?
Generated by the skeletal muscles (e.g.your gastrocnemius contracts when pushing off for a leap in dance)
36
What is an external force?
Comes from outside the body. e.g. friction, air resistance, weight
37
Examples of a horizontal force?
Friction and air resistance
38
Examples of vertical forces?
Gravity/Weight and Reaction
39
Examples of vertical forces?
Gravity/Weight and Reaction
40
Key aspect to friction?
Opposes motion when 2+ bodies in contact
horizontal force
41
what is static friction?
force exerted when there is no motion between 2 surfaces
42
what is sliding friction?
when 2 bodies in contact have a tendency to slip/slide over
43
What factors is friction affected by?
- The roughness of the surface
- The mass of an object
- The temperature of the 2 surfaces
44
Define air resistance
a force that acts in the opposite direction to the motion of a body travelling through the air (horizontal force)
45
Factors affecting air resistance?
- The velocity of the moving body
- The frontal cross-sectional area of the moving body (larger = greater resistance)
- The shape and surface characteristics of the moving body (streamlined= less resistance)
46
What happens to air resistance in water?
It is referred to as drag, due to water having a greater density.
47
What forces are added to free body diagrams?
- weight
- reaction
- friction
- air resistance
48
Define net force
the resultant force acting on a body when all other forces have been considered
discussed as unbalanced/balanced forces
49
What is a balanced net force?
2 or more forces acting on a body are equal in size, but opposite in direction
net force = 0 as there is no change is motion
50
What is an unbalanced net force?
when a force acting in one direction is larger then the force acting in the opposite direction
51
When is upward acceleration caused?
when the reaction force becomes greater than the weight force
52
What happens to net force when friction is equal to air resistance?
net force = 0
53
What happens when friction is greater than air resistance?
acceleration will occur
54
What happens when friction is smaller than air resistance?
deceleration will occur
55
Define impulse
the time taken for a force to be applied
56
What is the equation for impulse?
force x time (N/S)
57
How does Newton's 2nd law back up impulse?
If impulse increases, so does the rate of change of momentum
58
Define reaction
A force that starts where 2 bodies are in contact. This can be feet with ground, equipment with a ball etc
59
Transverse axis sporting example?
somersault
60
Sagittal axis sporting example?
Cartwheel
61
Longitudinal axis sporting example?
Triple spin in ice skating
62
When does angular motion occur?
when a force is applied outside the centre of mass (eccentric force)
63
What is torque?
A turning force
| the moment of force
64
What 2 things is torque dependent on?
1. The greater the size of the force, the greater the torque
| 2. Application of the same force further away from the axis will increase torque
65
What is the equation for torque / moment of force? (Nm)
Force(N) x Perpendicular distance from the fulcrum (m)
66
What is Newton's first law of angular motion?
A rotating body will continue in a state of constant angular momentum until acted upon by an external torque.
67
What is Newton's second law of angular motion?
The magnitude and direction of the torque determines the magnitude and direction of angular acceleration
OR
Angular acceleration is directly proportional to the torque acting and takes place in the direction of that torque
68
What is Newton's third law of angular motion?
For every rotational action, there is an equal and opposite rotational action.
69
Define angular displacement
The smallest change in angle between the starting and finishing point
70
In angular displacement, what is one radian equal to?
57.3 degrees
71
Define angular velocity
The rotational speed of an object and the axis about which the object is rotating
72
What is the equation for angular velocity? (rad/s)
Angular displacement / time
73
Define angular acceleration
The rate of change of angular velocity
74
What is the equation for angular acceleration? (rad/s2)
change in angular velocity / time
75
What is the moment of inertia?
The resistance of a body to change it's state of motion when rotating
76
What 2 factors is moment of inertia dependent on?
1. the mass of an object
2. how the mass is distributed from the axis of rotation (further away = bigger moment of inertia)
77
What is the equation for angular momentum?
angular velocity x moment of inertia
78
Define projectile motion
Refers to the movement of either an object or the human body as it travels through the air
79
What is a projectile?
Any object that once dropped continues in motion by its own inertia and is influenced only by the downward force of gravity
80
What are the 3 factors affecting the horizontal displacement of a projectile?
1. Angle of release
2. Velocity of release
3. Height of release
81
What is horizontal displacement?
The distance a projectile has moved between its point of release and its point of landing, measured as a straight line parallel to the ground
82
What is the optimum angle of release when release height and landing hight are the same?
45 degrees
83
What is the optimum angle of release when release height is greater than landing height?
less than 45 degrees
84
What is the optimum angle of release when release height is below landing height
greater than 45 degrees
85
What factors affect the flight path of different projectiles?
weight and air resistance
86
What projectile has a uniform curve and is symmetrical?
A true parabola
87
What projectile deviates from a true parabola?
A distorted parabola
88
What are the 2 vector components of parabolic flight?
horizontal component
vertical component
89
What is the rule of arrows and magnitude?
A larger arrow means a greater magnitude and a smaller arrow means a smaller magnitude
90
What is fluid mechanics?
The study of an object or the human body travelling through any liquid or gas
91
What is drag?
Drag (and lift) are types of dynamic fluid force
92
What are the main sports drag impacts?
- cycling
- swimming
- sprinting
- discus
- F1 racing
93
What are the essential things to remember when approaching an exam question on drag?
1. A drag force will always slow something down
2. Drag is a resistance force caused by a body moving through a fluid
3. Drag forces act in opposition to the direction of movement
4. Drag has a negative effect on velocity
5. The greater the cross sectional area, the greater the drag
94
Define streamlining
Shaping a body so it can move quickly through a fluid
95
What are the 2 types of drag?
1) Surface drag
2) Form drag
96
Explain surface drag
- Often called ‘skin drag’. It is the friction between the boundary layer of fluid and the surface of the object.
- Many sports want to decrease this
97
What affects surface drag?
- A smoother surface creates less friction - decreases surface drag
- A smaller surface area creates less friction - decreases surface drag
98
What is form drag?
Often called ‘shape drag’. It is the force affecting the leading edge of an object.
99
How can you decrease form drag?
1) Decrease in the frontal surface area decreases form drag
2) Streamlining a body/object decreases form drag
100
Key factors about streamlining?
- It includes a gradual taper towards the back of an object
- It allows fluid to move in layers/laminar flow
- Reduces fluid drag (gas and liquid)
101
What does a more streamlined object/body encourage?
Laminar flow
102
What does a less streamlined object/body encourage?
Turbulent flow
103
What is involved in laminar flow?
- fluid moves smoothly
- undertake smooth paths/layers
- less resistant to movement/velocity
104
What is involved in turbulent flow?
- irregular fluctuations
- changes in magnitude/direction
- increases friction/decrease velocity
105
How does slipstreaming reduce drag?
- a large drag hits from the front rider and provides less turbulent air for the cyclist behind - decreases form drag acting on the second rider
- saves 30% energy
106
What are the 3 factors that increase/decrease drag?
1. Velocity of the moving body → the greater the velocity, the greater the drag - can be solved by streamlining as much as possible
2. The cross-sectional area of the moving body → large cross-sectional area = increased drag , small cross-sectional area = reduced drag (may affect cyclists and ski jumpers)
3. The shape/surface of a moving body → more streamlined/aerodynamic - reduced drag , drag resistant clothing(smoother surface)
107
What is the Bernoulli principle?
- Bernoulli theorised that an increase in speed of a fluid occurs as a result of a decrease in pressure
- 𝗹𝗶𝗳𝘁 𝗳𝗼𝗿𝗰𝗲→ causes a body to move perpendicular to the direction of travel
- airfoil shape e.g. discus
108
What is downwards lift?
(F1 cars,speed skiers and cyclists)
When pushing the object into the ground, greater frictional forces are created
109
What is the purpose of a spoiler?
- due to the angle of a spoiler, air travelling over the top has a shorter distance
- the air above travels at a slower velocity
- the air above has a high pressure
- air travelling underneath has a longer distance
- the air travels at a greater velocity
- the air below travels at a lower pressure
Due to the pressure gradient this creates downward lift
110
Benefits of downwards lift?
- greater frictional forces between tyres and road
- tyres have firm grip on surface
- allows the bike/car to travel at faster speeds around the corners
- gives the cyclist/driver a faster time and so a greater chance of success
