Biomechanical Principles

Question 1

Define biomechanics?

Answer 1

The study of human movement and the effect of force and motion on performance.

Question 2

What things can biomechanics allow us to do?

Answer 2

• Maximise efficiency of performance
• Analyse performance
• Reduce acute injuries
• Design protective and comfortable equipment.

Question 3

Define motion?

Answer 3

The principle of something moving.

Question 4

Newton’s 1st Law?

Answer 4

INERTIA- a body will remain in a state of rest (stationary),until acted on by an external or unbalanced force.
Sporting Example?

Question 5

Newton’s 2nd Law?

Answer 5

ACCELERATION- a bodies rate of change of momentum is proportional to the force applied to it and acts in the same direction.
Sporting Example?

Question 6

Newton’s 3rd Law?

Answer 6

REACTION- for every action force applied to a body there is an equal and opposite reaction force.
Sporting Example?

Question 7

Define reaction force?

Answer 7

A force acting within Newton’s 3rd law that opposes the action force. When one object pushes against another.

Question 8

Define velocity?

Answer 8

The rate of change of displacement.

Question 9

What’s the equation for velocity?

Answer 9

Velocity= distance (m) =m/s

time (s)

Question 10

Define momentum?

Answer 10

The quantity of motion possessed by a moving body.

Question 11

What’s the equation for momentum?

Answer 11

Momentum= mass * velocity =kgm/s

Question 12

Define acceleration?

Answer 12

The rate of change in velocity.

Question 13

What’s the equation for acceleration ?

Answer 13

Acceleration= (final velocity-initial velocity) =m/s/s
time taken

Question 14

Define force?

Answer 14

A push or pull that alters the state of motion of an object.

Question 15

What’s the equation for force?

Answer 15

Force= mass* acceleration =N

Question 16

What are internal forces?

Answer 16

The forces created by muscular contractions acting on the skeleton.

Question 17

What are external forces?

Answer 17

The forces created outside the body.

1. Weight
2. Reaction force
3. Air resistance
4. Friction

Question 18

What affects can force have?

Answer 18

1. Create a motion
2. Accelerate a force
3. Decelerate a force
4. Change the direction of a body
5. Change the shape of a body

Question 19

Define stability?

Answer 19

The ability of a body to resist motion and remain at rest

Question 20

What four things affect stability?

Answer 20

1. Mass of the object
2. Height of COM
3. Base of support
4. Line of gravity (if goes through base of support= increased stability)

Question 21

Define COM?

Answer 21

The point at which the body is balanced in all directions, whilst also being a point of rotation.
Can be MANIPULATED to improve performance.

Question 22

Vertical forces?

Answer 22

Weight- the gravitational pull that the earth exerts on a body. ALWAYS ACTS THROUGH THE COM (N)
Reaction force- an equal and opposite force in response to gravity. ALWAYS ACTS THROUGH THE LIMB IN CONTACT WITH THE GROUND. (N)

Question 23

Horizontal forces?

Answer 23

Friction- the force that opposes the motion of two surfaces in contact. ALWAYS ACTS THROUGH LIMB IN CONTACT WITH GROUND (N)
Air resistance- the force that opposes the motion of a body travelling through the air. ALWAYS ACTS THROUGH COM (N)

Question 24

Factors affecting friction?

Answer 24

1. Roughness of the surfaces in contact. eg:spikes
2. Roughness of the ground eg: rubber track
3. Temperature of surfaces eg: heating F1 tyres
4. Mass/size of body eg: carbon fibre

Question 25

Factors affecting air resistance?

Answer 25

1. Velocity, faster = greater ar.
2. Shape =streamlining
3. Cross-sectional area
4. Smoothness of surface eg: licra

Question 26

Balanced forces?

Answer 26

• 2 or more opposing forces are equal in size.
• No change in motion
• Constant velocity
• Net force= 0

Question 27

Unbalanced forces?

Answer 27

• 2 or more opposing forces are unequal in size and one EXCEEDS the other
• Change in motion
• Acceleration or deceleration
• Net force= positive or negative

Question 28

How is the COM used by a Fosby Flop high jumper to maximise performance?

Answer 28

TAKE OFF
Height of COM increased as performer lifts knees
COM remains in the body

FLIGHT/ ROTATION 
High jumper bends forwards 
Arches back 
COM moved from inside body to create an axis of rotation 
"HIGH JUMPER ROTATES ABOUT THEIR COM" 
"Greater height achieved"