Flashcards in U3 AOS1 Pt2 Deck (67):

1

## Biomechanics

### Science that studies living things from a mechanical perspective

2

## What is a force

###
A push or pull

Mass x Acceleration

3

## How do forces affect objects

###
Change its shape (stretch, squash, twist)

Move the object (speed up, slow down, change direction)

4

## Types of forces

###
Gravity

Weight

Friction

Drag

5

## Gravity

###
A constant force that acts through the centre of mass of an object towards the earth

9.8m/s2

6

## Friction

###
Occurs when two surfaces come into contact with each other, opposing the motion of an object

To start an object moving, you must overcome its friction by applying a greater force

Influenced by surface imperfections and surface area

7

## Drag Force: Air and Water Resistance

###
Caused by the collision of air and water particles on the object, opposing its motion

Affected by air density, speed, cross sectional area of object

Increase speed means increase drag

Decrease surface area and use tight clothing

8

## Weight and Mass

###
Mass is the amount of matter an object is made up of (kg)

Weight is the force exerted upon a body by gravity (N)

Weight = Mass x Gravity

9

## Inertia

###
Tendency of an object to resist a change in its state of motion, whether at rest or constant velocity

Greater mass=greater inertia=greater force to move object

10

## Momentum

###
Measure of the amount of motion an object has and its resistance to changing that motion

Momentum = Mass x Velocity

11

## Conservation of momentum

###
Momentum is conserved in an isolated system where there are no external factors acting

"Total momentum of systems before the collision is equal to the total momentum after the collision'

12

## Summation of Momentum

###
Sequential and coordinated movements of each body segment to produce maximum velocity

Max Vel result from momentum generated from body parts closer to centre of gravity to those further away

13

##
How to summate momentum

###
- use as many body parts as possible

- use stronger, larger muscles before quicker and smaller muscles

- coordinating the sequencing of body parts so momentum can be transferred from one muscle group to the next

- create a stable base of support for Movement to occur around

14

## Impulse

###
change in momentum of an object, mass in motion

Impulse = Force x Time

Manipulating impulse can reduce injury (hands while catching)

Larger force over shorter time or smaller force over longer time

15

## Newtons 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 a external force

16

## Newtons Second Law

###
Law of Acceleration

A force applied to an object will produce a change in motion in the direction of the force applied that is directly proportional to the size of force

17

## Newtons Third Law

###
Law of Action Reaction

For every action there is an equal and opposite reaction

18

## Torque

###
The turning effect caused by an eccentric force (one that doesn't act through the objects centre of gravity)

Force x lever arm

19

## Newtons First Law of Angular Motion

### The angular momentum of a body remains constant unless acted upon by an external torque

20

## Newtons 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

21

## Newtons Third Law of Angular Motion

### For every torque there is an equal and opposite torque

22

## Angular momentum

### Quantity of angular motion of an object

23

## Moment of inertia

###
The resistance of an object to changes in its state of angular motion

Mass x Radius2

Product of distribution of mass of object and the axis about which it rotates

24

## Conservation of Angular Momentum

###
Angular momentum is conserved when body is in flight

As angular momentum is constant, and mass is constant, then there is a trade off between moment of inertia and velocity

25

## General motion

### Combination of linear and angular motion

26

## Linear motion

###
Movement of the body where all parts move in the same direction at the same time along a line

Curved line= curvilinear

Straight line= rectilinear

27

## Angular motion

### Movement of a body part around an axis of rotation

28

## Projectile motion

### The movement of an object through the air

29

## Distance

### Measures the path travelled from start to finish regardless of direction

30

## Displacement

###
Change of position from initial position to final position

Direction of motion is important

31

## Speed

###
Ratio of the distance covered to the time taken

Speed= distance/time (m/s)

32

## Velocity

###
Ratio of displacement or change in position to the time taken

Velocity = displacement/time (m/s)

33

## Acceleration

###
Change in velocity in a given period of time

Acceleration = change in velocity/change in time (m/s2)

Can be positive or negative

34

## Angular distance

### Sum of all angular changes the body undergoes

35

## Angular displacement

### Difference between the initial and final angular position of an object

36

## Angular speed

### Angular distance covered divided by the time taken to complete the motion

37

## Angular velocity

### Rate of change of the angular displacement of a body over time

38

## Angular acceleration

### Rate of change of angular velocity

39

## Projectile

### An object or body that is launched into the air and affected by the forces of gravity and air resistance

40

## Path of an object is affected by

###
Angle of release

Speed of release

Height of release

41

## Horizontal Trajectory

### Projection at 0° or perfectly horizontal

42

## Oblique trajectory

### Occurs when the angle of projection is between 0° and 90° (parabolic)

43

## Vertical trajectory

### Object travels straight up and down

44

## Best angle for covering the greatest horizontal distance

### 45°

45

## Speed of release

### Greater speed of release = greater horizontal range of projectile

46

## Height of release

### Difference between the height of projectile release from height at which it lands

47

## Equilibrium

### When all forces and torques are balanced

48

## Static equilibrium

###
Body/object must not be moving or rotating

-sum of all vertical, horizontal forces and torques must be zero

49

## Dynamic equilibrium

### When the body/object is moving with a constant velocity, no change in speed or direction

50

## Stability

### Resistance to the disruption of equilibrium

51

## Balance

### Ability to control equilibrium

52

## Factors affecting stability

###
Base of support

Centre of gravity

Body mass

Friction between object and surface its in contact with

53

## Base of Support

###
Generally, larger BOS the greater stability

Moving one foot behind the other increases forward/backwards stability

Moving one foot further away midline increases side to side stab

Point of contact with the supporting surface

54

## Centre of Gravity

###
Point around which the body's weight is balanced

Usually found near naval

Lowering COG increases stability

55

## Line of gravity

###
Direction in which the gravity acts through the centre of gravity

-when LOG acts through centre of BOS, stability increased

- stability decreased when LOG moves to outside edge of BOS

56

## Body mass

### Greater mass of object, greater force required to move it, greater stability

57

## Friction

### Increasing friction between object and surface it is contact with increases stability

58

## What is a lever

### A simple machine consisting of a rigid bar that can be made to rotate around an axis in order to exert a force on another object

59

## Components of a lever

###
Axis

Resistance

Force

60

## 1st class lever

###
Resistance and force applied in the same direction with axis in middle

(Seesaw, extending head)

61

## 2nd class lever

###
Resistance and force applied in opposite directions

Resistance closer to axis and force further away

(Wheelbarrow and standing on tip toes)

62

## Third class lever

###
Resistance and force applied in opposite direction

Force closer to axis and resistance further away

(Catapult, flexing elbow)

63

## Mechanical advantage

###
Ratio of force arm to resistance arm

Force arm/resistance arm

Force arm: distance from axis to force

Resistance arm: distance from axis to resistance

64

## Mechanical advantage greater than one

###
Greater force

Less force to move resistance

65

## Mechanical advantage less than one

### Increased range of motion and angular speed

66

## Lever length

### Longer levers have greater inertia and therefore more difficult to swing

67