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Pe A-level HK > Biomechanics > Flashcards

Biomechanics Flashcards

3.1 principles - newton and 3.2 stability and lever systems

1
Q

What is Biomechanics?

A

Study of human movement and the effect of force and motion on sports performance

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2
Q

How does the laws and principles enables performers and coaches

A

Analyse performance
maximise perfomance
reduce or prevent injuries
design equipment

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3
Q

What is Newton’s first laws of motion?

A

Law of Inertia-
A body continues in a state of rest or uniform velocity unless acted upon by an external or unbalanced

Eg- the greater the mass of the sprinter the greater the force needed to accelerate away from the blocks.

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4
Q

What is inertia-

A

The resistance of a body to change its state of motion

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5
Q

Apply Newtons first law of motion for a 100m sprinter?

A

The 100m sprinter will remain at rest in the blocks until an external force large enough to overcome their inertia creates motion.
Equally when the sprinter reaches constant velocity, they should continue at that constant velocity until an external or unbalanced force acts upon them to change.

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6
Q

What is velocity

A

The rate of change in displacement. This is a term used throughout this chapter and although closely related to speed, includes a directional element

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7
Q

What is Newton’s second law of motion?

A

law of acceleration-
“A body’s rate of change in momentum is proportional to the size of the force applied and acts in the same direction as the force applied”

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8
Q

Apply newtons second law

A

The greater the force applied to the sprinter the greater the rate of change in momentum and therefore acceleration away from the blocks. The force is applied in a forward direction so the sprinter drives towards the line.

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9
Q

What is momentum

A

the quantity of motion possessed by a moving body

Momentum (kgm/s) = Mass X velocity

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10
Q

What is acceleration?

A

The rate of change in velocity.

Acceleration (m/s/s) = (Final velocity - initial velocity) / time

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11
Q

What is newtons third law of motion

A

law of reaction

“For every action force applied to a body there is an equal and opposite reaction force”

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12
Q

Apply newtons third law

A

when the 100m sprinter applies a down and backward action force into the blocks, the blocks provide an equal and opposite up and forward reaction force to the sprinter to rive them out the blocks

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13
Q

Calculation for velocity

A

Displacement m / time taken s
(m/s)

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14
Q

Calculation for momentum

A

mass x velocity
(kgm/s)

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15
Q

Calculation for acceleration

A

(Final velocity- inital) / time taken
(m/s/s)

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16
Q

What is force

A

A push or a pull that alters the state of motion of a body

Internal force generated by the contraction of skeletal muscle

External force comes from outside the body and acts upon it.

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17
Q

calculation of force

A

Mass x acceleration
measured in newtons (N)

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18
Q

What are the 5 effects force can have?

A

1- Can create motion
2- Can accelerate a body
3- Can decelerate a body
4- Can change the direction of a body
5- Can change the shape of a body

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19
Q

using a football penalty- explain how force affects it

A

1- The football will remain at rest on the penalty sport until a force is applied
2- The greater the force applied by the footballers foot to the ball, the greater the rate of acceleration towards the goal.
3- the ball moves through the air towards the goal, the force of air resistance will act in the opposite direction and slow it down
4- as the goalkeeper dives to save a high corner shot, he will apply a force from his hands to the ball, changing its direction pushing it way from goal
5- if the goalkeeper fails to make the save, the force of the ball coming into contact with the net will make the net change shape

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20
Q

What is net force?

A

The sum of all forces acting on a body. (also known as resultant force)

If a net force is present, there is a change in motion as the forces are unbalanced

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21
Q

What are horizontal and vertical forces in netforce

A

the vertical that push a body up and pull a body down and
the horizontal forces that push a body forwards and pull it backwards

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22
Q

What are balanced forces

A

These occur when two or more forces acting on a body are equal in size and opposite in direction.

Net force = 0, the body will remain at rest or in motion with constant velocity

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23
Q

What are unbalanced forces

A

These occur when two forces are unequal in size and opposite in direction.

A net force will be present and the body will change its state of motion, either accelerating or decelerating

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24
Q

What are the vertical forces

A

weight and reaction

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25
Q

What is weight

A

gravitational pull that earth exerts on a body and is measured in newtons

weight is always present and acts downwards from the body’s centre of mass.

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26
Q

calculation of weight

A

mass x acceleration due to gravity
(N)

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27
Q

What is Reaction

A

Is the equal and opposite force exerted by a body in response to the action force placed upon it

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28
Q

What is reaction measured in

A

Newtons

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29
Q

What are the Horizontal Forces

A

Friction and Air resistance

30
Q

What is friction

A

The force that opposes the motion of two surfaces in contact

31
Q

What is Friction measured in?

A

Newtons

32
Q

What factors affect friction?

A

Roughness of ground surface
Roughness of contact surface
Temperature
Size of normal reaction

33
Q

How does the roughness of the ground surface affect friction?

A

Increased roughness = Increased friction

34
Q

How does the roughness of the contact surface affect friction?

A

Increased roughness = friction increased

35
Q

How does temperature affect friction?

A

Increased temp of ground and contact surface = friction increased

36
Q

How does increasing the size of normal reaction affect friction?

A

Increasing size of normal reaction = increased friction

37
Q

What is air resistance?

A

A force that opposes the motion of a body traveling through the air

38
Q

What is air resistance measured in?

A

Newtons

39
Q

What factors is air resistance affected by?

A

Velocity
shape
Frontal-cross sectional area
Smoothness of surface

40
Q

How does velocity affect air resistance

A

Increasing velocity= increased air resistance

41
Q

How does shape effect air resistance

A

More aerodynamic the shape = lower air resistance

42
Q

How does frontal cross-sectional area affect air resistance?

A

decreasing frontal cross-sectional area= decrease air resistance

43
Q

How does smoothness of surface affect air resistance?

A

Increasing smoothness = air resistance decrease

44
Q

What is streamlining?

A

The creation of smooth air flow around an aerodynamic shape to minimise air resistance

45
Q

What is a free body diagram?

A

A clearly labelled sketch showing all of the force acting on a body at a particular instant in time

46
Q

What is the origin and direction of the arrow for weight in a free body diagram

A

From the centre of mass - downwards vertically

47
Q

What is the origin and direction of the arrow for reaction in a free body diagram?

A

From the point of contact extending vertically upwards

48
Q

What is the size of the arrow and relationship between weight?

A

If weight is equal in size to reaction (W=R), net force is zero.
Forces are balanced (equal in size and opposite in direction)

Therefore, the body will remain at rest.

49
Q

What is the size of the arrow and relationship between weight?

A

If reaction force is greater than weight (R>W), net force is positive.
Forces are unbalanced and acceleration in an upward direction will occur.

50
Q

Origin and direction of arrow of friction?

A

From the point of contact and usually extending horizontally in the same direction as motion (parallel to the surfaces)

51
Q

What are the components of a lever

A

Fulcrum
Load
Effort

52
Q

What are levers

A

important in understanding how the body moves

53
Q

What is the fulcrum

A

The pivot point eg a joint

54
Q

What is the load

A

The resistance or weight being moved (eg body weight)

55
Q

What is the effort?

A

The force applied (eg muscle contraction

56
Q

What is a first class lever

A

The fulcrum is between the load and the effort (eg neck extension - header in football)

57
Q

What is the mechanical advantage of first-class levers

A

If the effort arm is longer than the load arm (less effort to move a large load

58
Q

What is the mechanical disadvantage of first class levers

A

if load arm is longer- more effort to lift a smaller load

59
Q

What is a second class lever

A

The load is between the effort and the fulcrum (eg calf raises- ball of foot is fulcrum

Move large load with little effort

60
Q

Are second class levers a mechanical advantage or disadvantage

A

Always advtanage

61
Q

What is a third class lever

A

The effort is between the load and the fulcrum (most movements in the body)

Greater range of motion and speed

62
Q

Are second class levers a mechanical advantage or disadvantage

A

Always disadvantage

63
Q

What is linear motion

A

Movement in a straight line

64
Q

What is distance

A

The total path traveled by a body

65
Q

What is displacement

A

The shortest straight line distance between the start and finish points

66
Q

What is speed

A

The rate at which an object covers distance
speed = distance / time

67
Q

What is velocity

A

The rate of change of displacement

velocity= displacement/ time

68
Q

What is acceleration

A

The rate at which velocitu changes

acceleration = change in velocity / time

69
Q

What is momentum

A

The quantity of motion possessed by a moving body
momentum = mass x velocity

70
Q
A

Pe A-level HK (5 decks)

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