LEWIS: Mechanics Of Movement Flashcards
(101 cards)
1
Q
Linear motion is
A
A motion in a straight or curved line with all body parts moving the same distance at the same speed in the same direction
2
Q
Linear motion is measured in 10 ways
A
Mass
Weight
Distance
Deceleration
Speed
Velocity
Inertia
Momentum
3
Q
Scalar quantities are described in terms of
A
Magnitude
4
Q
Scalar measurements:
A
Mass
Distance
Speed
Inertia
5
Q
Vector quantities are described in terms of
A
size and direction
6
Q
Vector measurements are
A
Weight Acceleration Deceleration Displacement Velocity Momentum
7
Q
Mass is
A
Body tissue
Scalar
8
Q
Weight is the
A
Force on a given mass due to gravity
Vector
8
Q
Distance and displacement are used to describe a
A
Body’s motion
9
Q
Inertia is the resistance
A
An object has to a change in its state of motion
Scalar
Newton’s 1st law
Bigger the mass the larger the inertia needed
10
Q
Distance is the length of the path a body follows when
A
Moving to a point
E.g. 400m rubber
11
Q
Displacement is the length of a straight line joining the
A
Start and finish points
E.g. 200m race on the track
12
Q
Speed is the rate of change of
A
Position
Scalar
13
Q
Equation for speed =
A
Distance(m)/time(s)
14
Q
Equation for velocity =
A
Displacement(m)/time(s)
15
Q
Velocity is the rate of change of position with reference to
A
Direction
Vector
16
Q
Acceleration and deceleration are the rate of change in
A
Velocity
17
Q
Acceleration =
A
Velocity increases
19
Q
Deceleration =
A
Velocity decreases
20
Q
Acceleration and deceleration =
A
vector
21
Q
Acceleration =
A
change in velocity (ms-1) / time (s)
22
Q
Change in velocity =
A
final velocity - initial velocity
23
Q
Momentum is the product of
A
mass and velocity of an object
24
Q
Momentum (kg/m/s-1) is calculated using:
A
mass (kg) x velocity (m/s-1)
25
Momentum =
vector as it has magnitude and direction
26
Momentum is a closed system, which means total momentum is conserved. So when 2 objects collide the total momentum stays...
the same
27
forces can be either :
internal or external
28
internal forces are generated through the contraction of
skeletal muscles
29
external forces come from outside the body, e.g.
air resistance and friction
30
2 factors affect a generated force:
size (dependent on the size and number of muscle fibres used)
direction (force applied through the middle = move in same direction as force)
31
Applying a force straight through the centre =
linear motion
32
Applying a force off-centre results in spin =
angular momentum
33
force =
mass x acceleration
34
vertical forces:
weight
| reaction
35
horizontal forces:
friction
| air resistance
36
(VF) weight is a
gravitational force that the Earth exerts on a body pulling it downwards
37
(VF) reaction occurs whenever
2 bodies are in contact with one another (Newton's 3rd law)
38
(HF) Friction occurs whenever there are 2 bodies in contact with each other that try to move over one another. It acts in opposition to motion and resists the sliding/slipping motion of
2 surfaces
39
(HF) Air resistance opposes the motion of a body travelling through the
air
40
Air resistance depends on the:
- velocity of the moving body (greater velocity = greater resistance)
- cross-sectional area of the moving body (larger cross-section=greater air resistance)
- shape and surface characteristics of the moving body (streamlined = less resistance)
41
FREE BODY DIAGRAMS: (VF) Weight is always drawn
down from the centre of mass
42
FREE BODY DIAGRAMS: (VF) Reaction starts from where 2 bodies are in
contact with one another, e.g. foot to floor or sports equipment and a ball
43
FREE BODY DIAGRAMS: (HF) Friction starts from where 2 bodies are in contact and is opposite to the direction of any
potential slipping (usually drawn in the same direction as motion)
44
FREE BODY DIAGRAMS: (HF) Air resistance is drawn from the
centre of mass and opposes the direction of motion of the body
45
Net force is the resultant force acting on a body when all other forces have bee
considered
46
Net force is often discussed in terms of
balanced versus unbalanced forces
47
Balanced force is when there are 2 or more factors acting on a body that are
equal in size but opposite in direction
48
Balanced force = 0 net force and no change in motion so is directly related to
Newton's first law
49
Unbalanced is when a force acting in one direction on a body is
larger than the force acting in the opposite direction
50
Impulse is the product of the
average size of the force acting on a body and the time for which that force is applied
51
Impulse (Ns) is calculated as:
force x time
52
The longer the contact the
greater the impulse
53
impulse can be used to add speed to a body or object. Speeding up a body or object can be achieved by increasing the amount of
muscular force that is applied
54
Example of greater force due to impulse =
push pass
55
Speeding up of an object can be achieved by increasing the amount of time for which the force is
applied
56
Impulse is represented by a
force-time graph
57
Positive impulse occurs for
acceleration at take off
58
Negative impulse occurs when foot lands to provide a
braking action
59
start of 100m race - the net impulse is positive, which results in
acceleration
60
middle of 100m race - the net impulse is equal which results in no acceleration or deceleration, so the sprinter is running at a
constant velocity
61
end of 100m race - the net impulse is negative, which results in
deceleration
62
projectile motion refers to the motion of either an object or the human body being 'projected' into the air at an
angle
63
3 factors that determine horizontal distance that a projectile can travel:
angle of release
height of release
velocity of release
64
(Angle of release) to achieve maximum horizontal distance, the angle of release of the projectile is important. The optimum angle of release is dependent upon release height and landing height. When both are equal the optimum angle =
45 degrees
65
(Angle of release) if release height = greater than the landing height, then the optimum angle of release is less than
45 degrees = shot putter
66
(Angle of release) if release height = lower than landing then the optimum angle is greater than
45 degrees = basketball set/jump shot
67
(Velocity of release) the greater the release velocity of a projectile, the greater the
horizontal distance travelled, e.g. throwing events (javelin/hammer)
68
(height of release) a greater release height results in an increase in
horizontal distance, e.g. taller = further
69
Projectiles are affected by
weight
| air resistance
70
projectiles with a large weight = small air resistance and follow a
parabolic pathway
71
projectiles with a lighter mass (shuttlecock) are affected by air resistance and this causes them to deviate from
parabolic pathway
72
During parabolic pathway:
| horizontal component remains:
the same throughout (point of release, highest point, point immediately before landing)
73
(PP) Vertical component
Point of release:
Highest point of flight:
Point immediately before landing:
large
none (weight and reaction force equaled)
larger due to gravity
74
Angular motion is the movement around a
fixed point or axis = somersault
75
Angular motion occurs when a force is applied outside the
centre of mass
76
3 axes of rotation:
```
transverse = horizontal across body (somersault)
frontal = front to back (cartwheel)
longitudinal = top to bottom (spinning ice skater)
```
77
angular momentum depends on the
moment of inertia
| angular velocity
78
Torque (moment) is a rotational force. It causes an object to turnabout its axis of rotation. Movement of a force or torque can be calculated as:
force(N) x perpendicular distance from axis of rotation (m)
79
Angular distance is the angle rotated about an axis when moving from one position to
another
80
Angular acceleration is the rate of change of velocity during
angular movement
81
angular velocity is the rate of movement in
rotation
82
angular displacement is the amount of rotation of a point, line/body in a specified direction about an
axis
83
angular momentum is conserved unless an external torque acts upon it.
Angular momentum =
angular velocity x moment of inertia
84
Newton's first law (law of inertia): a body will continue in its state of rest or motion in a straight line, unless
external forces are exerted upon it
85
NFL/LOI example = point in race where the runner has reached a
OR
Sprinter will remain in set position until force is applied to
constant velocity (80-90m in 100m)
change their state
86
Newton's second law (law of acceleration): the rate of change of momentum of a body is proportional to the force causing it and the change that takes place in the direction in which the force
force =
acts
mass x acceleration
87
NSL/LOA example = force applied to ball, acceleration is proportional to the size of the force - the harder the ball is kicked, the
sprinter = greater force (muscular) applied to blocks =
further and faster it will go
greater acceleration
88
Newton's third law (law of reaction): to every action there is an equal and opposite
reaction
89
NTL/LOR example = footballer jumps up to win a header, a force is exerted on the ground in order to gain height. At the same time, the ground exerts an upward force (equal and opposite) upon the
footballer
90
NFL on angular motion: a rotating body will continue in its state of angular motion unless an
external force (torque) is exerted upon it
91
NSL on angular motion: the rate of change of angular momentum of a body is proportional to the force causing it and the change that takes place in that direction. I.e. leaning forwards will create
more angular momentum than standing straight
92
NTL on angular motion: when a force is applied by one body to another, the second body will exert an equal and opposite force on the other body. I.e. when in a dive, when changing position from a tight tuck to a
layout position
93
inertia = resistance to change in motion
| Moment of inertia (MOI) is therefore resistance of a body to
angular motion
94
The greater the mass of a body/object, the greater the resistance to change and therefore the greater the
moment of inertia
95
The closer the mass is to the axis of rotation the easier it is to turn so MOI is
low, e.g. tuck
96
increasing the distance of the distribution of mass from the axis of rotation will increase the
moment of inertia, e.g. pike/straight
97
angular momentum =
angular velocity x moment of inertia
98
angular momentum is
conserved
99
speed of a spin depends on
MOI and angular velocity
100
(Spin) increase in MOI =
decrease in AV (vice versa)
101
Ground reaction force =
the equal and opposite force given to a performer who exerts a muscular force into the ground (NTL)
