Flashcards in LEWIS: Mechanics Of Movement Deck (101):

1

## Linear motion is

### 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

## Linear motion is measured in 10 ways

###
Mass

Weight

Distance

Deceleration

Speed

Velocity

Inertia

Momentum

3

## Scalar quantities are described in terms of

### Magnitude

4

## Scalar measurements:

###
Mass

Distance

Speed

Inertia

5

## Vector quantities are described in terms of

### size and direction

6

## Vector measurements are

###
Weight

Acceleration

Deceleration

Displacement

Velocity

Momentum

7

## Mass is

###
Body tissue

Scalar

8

## Weight is the

###
Force on a given mass due to gravity

Vector

8

## Distance and displacement are used to describe a

### Body's motion

9

## Inertia is the resistance

###
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

## Distance is the length of the path a body follows when

###
Moving to a point

E.g. 400m rubber

11

## Displacement is the length of a straight line joining the

###
Start and finish points

E.g. 200m race on the track

12

## Speed is the rate of change of

###
Position

Scalar

13

## Equation for speed =

### Distance(m)/time(s)

14

## Equation for velocity =

### Displacement(m)/time(s)

15

## Velocity is the rate of change of position with reference to

###
Direction

Vector

16

## Acceleration and deceleration are the rate of change in

### Velocity

17

## Acceleration =

### Velocity increases

19

## Deceleration =

### Velocity decreases

20

## Acceleration and deceleration =

### vector

21

## Acceleration =

### change in velocity (ms-1) / time (s)

22

## Change in velocity =

### final velocity - initial velocity

23

## Momentum is the product of

### mass and velocity of an object

24

## Momentum (kg/m/s-1) is calculated using:

### 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