biomechanical principles

Question 1

newton’s first law

Answer 1

•law of inertia
•an object will continue in as state of constant velocity until compelled to change by an external force

Question 2

newton’s second law

Answer 2

•law of acceleration
•an object will accelerate proportional to the force acting and in the direction of that force
• mass x acceleration = force

Question 3

newton’s third law

Answer 3

•law of reaction
•for every action there is an equal and opposite reaction

Question 4

force definition

Answer 4

a push or pull that tends to alter the state of motion of a body

Question 5

momentum force

Answer 5

the amount of motion possessed by a moving body

Question 6

acceleration definition

Answer 6

the rate of change in velocity

Question 7

weight definition

Answer 7

the force that the earth exerts on the mass of a body

Question 8

velocity definition

Answer 8

rate of change in displacement of the shortest route from A to B

Question 9

force equation

Answer 9

force= mass x acceleration

Question 10

momentum equation

Answer 10

momentum = mass x velocity

Question 11

acceleration equation

Answer 11

acceleration = force / mass
or
acceleration = change in velocity / time

Question 12

velocity equation

Answer 12

velocity = displacement (distance) / time

Question 13

centre of mass definition

Answer 13

A point at which mass is distributed evenly in all directions.

Question 14

factors effecting centre of mass

Answer 14

•distribution of mass
•movement of limbs
•uniformity if shape

Question 15

centre of mass and distribution of mass

Answer 15

In the human body centre of mass is constantly moving depending on the distribution of the mass.

Question 16

centre of mass and uniformity of object

Answer 16

In a uniform object (something with the same density from the centre to all parts), like a shot, the centre of mass remains in the middle at all times.

Question 17

centre of mass and movements of limbs

Answer 17

In unique scenarios, like the Fosbury Flop on the right, the centre of mass may move outside of the physical body.

Question 18

stability

Answer 18

a measure of how a body is moved from a position of equilibrium or balance.

Question 19

line of gravity

Answer 19

an imaginary lie extending vertically downward to the ground from the centre of mass

Question 20

base of support

Answer 20

the area enclosed by the points of contact with the ground.

Question 21

factors effecting stability

Answer 21

1. Low centre of mass – The lower we are to the ground and the shorter the line of gravity, the more stable we are. Think a rugby player in a tackle
2. Large base of support and points of contact with the ground – The bigger the base of support the more stable we are. Think of a headstand compared to a handstand.
3. Large mass – The larger our mass the larger our stability. Try shifting a heavy object off a plateau compared to a lighter one
4. Line of gravity in the middle of base of support – Again consider a handstand, as soon as you lean you legs one way or the other you are likely to be unstable.

Question 22

balanced forces

Answer 22

When two or more forces acting on a body are equal in size but opposite in direction. All forces cancel out .

Question 23

unbalanced forces

Answer 23

When two or more forces acting on the body do no cancel out. This means a net force acts.

Question 24

net force

Answer 24

The overall force acting on a body when all forces are considered. Also know as the resultant force.

Question 25

vertical forces

Answer 25

• weight - acts down from the centre of mass

• ground reaction force - acts upwards from the points of contact with the ground, in reaction to all downwards forces.

Question 26

horizontal forces

Answer 26

•friction - opposes the sliding motion of one surface across another

•Air Resistance – acts against the direction of motion, opposing the movement of the body through the air

Question 27

factors affecting friction

Answer 27

•Characteristics/roughness of surface of sole of footwear
•Characteristics/roughness of playing surface
•Weight/normal ground reaction force (the force pushing the two surfaces together)
•Temperature - heated tyres increase friction between the rubber and the track

Question 28

factors affecting air resistance

Answer 28

•Velocity
•Frontal cross-sectional area
•Streamlining and shape
•Surface characteristics
•Mass

Question 29

friction and air resistance

Answer 29

•If the athlete is moving forwards the Friction must be bigger than the Air Resistance
•If Air Resistance is bigger than Friction it means they will be decelerating, but direction of motion will still be forwards
•If the athlete is standing still there won’t be horizontal forces acting on them

Question 30

weight and reaction

Answer 30

If the athlete isn’t moving up or down the Weight and Reaction forces should be the same length

Question 31

class 1 lever system

Answer 31

• fulcrum

Question 32

class 1 lever example

Answer 32

• elbow extension
• neck movement

Question 33

class 1 mechanical advantage / disadvantage

Answer 33

dependent of where the fulcrum sits

Question 34

class 2 lever system

Answer 34

• load/resistance

Question 35

class 2 lever example

Answer 35

planter flexion

Question 36

class 2 lever advantage/disadvantage

Answer 36

longer effort arm
- this mean there is less effort needed to move a heavy load

however: lack ROM and speed

Question 37

class 3 lever system

Answer 37

• effort

Question 38

class 3 lever example

Answer 38

any movements
other than ankle and elbow extension

Question 39

class 3 lever advantage/disadvantage

Answer 39

this means you have more ROM and speed

however: means heavy loads need a lot of effort

Question 40

methods of technology in improving technique

Answer 40

• limb kinematics
• force plates
• wind tunnels

Question 41

limb kinetics

Answer 41

• produces 2D moving model of movement
• shows technical performance
• maps joint movement
• all movement can be graphed and analysed

Question 42

force plates

Answer 42

• measured ground reaction force
• gain quantities of balance and gait
• measure vertical and horizontal force
• combines with limb kinematics

Question 43

wind tunnels

Answer 43

• measures aerodynamics
• pressure sensors
• tubular passage