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Josh's Decks > biomech deck > Flashcards

biomech deck Flashcards

1
Q

what is newtons first law

A

“A body continues in a state of rest or moving with constant velocity in a straight line, unless acted upon by an external force.”

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2
Q

what is newtons second law

A

“When a force acts on an object, the rate of change of momentum experienced by the object is proportional to the size of the force and takes place in the direction in which the force acts.”

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3
Q

what is newtons third law

A

“For every action, there is an equal and opposite reaction.”

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4
Q

what is centre of mass

A

The point where the mass of the body tends to be concentrated and balanced in all directions.”

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5
Q

what does The centre of mass depend on

A

The body position
The athlete’s body itself (shape)
Gender

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6
Q

A stable body position will enable an athlete to…

A

resist motion

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7
Q

The stability of an athlete is determined/ affected by:

A

The mass of the body
Size of the base of support
Height of the centre of mass
No. of points in contact with the surface
Proximity of the line of gravity to the centre of the base of support

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8
Q

equation of force

A

Force = Mass x Acceleration (F=Ma)

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9
Q

force is defined as

A

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

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10
Q

Force is essential to create motion and can do the following 5 things:

A 
Create motion
Accelerate a body
Decelerate a body
Change the direction of a body
Change the shape of a body
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11
Q

net force definition

A

The overall force acting on
a body when all individual
forces have been considered.

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12
Q

balanced forces definition

A

Balanced Forces: When two or more forces acting on a body are equal in size

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13
Q

unbalanced forces definition

A

Unbalanced Forces: When forces acting on a body are unequal in size.

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14
Q

vertical forces

A

Weight & Reaction Force

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15
Q

horizontal forces

A

Friction & Air Resistance

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16
Q

define weight

A

Gravitational force that the Earth exacts on the body (Downwards).

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17
Q

define reaction force

A

Whenever there is a point of contact between two bodies, there will always be a reactionary force.

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18
Q

define air resistance

A

This is the force that opposes motion of a body travelling through the air.

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19
Q

define friction

A

The force that opposes the motion of two surfaces in contact. Measured in Newtons (N).

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20
Q

how can friction be affected

A

Roughness or smoothness of footwear or object in contact with the ground.

Roughness or smoothness of the ground or court.

Size of the down force (Think about N3)

Temperature of Surface – Depending on the characteristics of the bodies in contact.

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21
Q

how can air resistance be affected

A

Shape of object: The larger cross-sectional area of a body, the greater the air resistance will be.

Speed/velocity of release: The greater the velocity of the body travelling, the greater air resistance a body will encounter.

Frontal cross-sectional area: Decreasing this area decreases air resistance.

By increasing smoothness, air resistance decreases. Eg. Smooth lycra suits worn by sprinters.

22
Q

what are the fulcrum, load and effort

A

Fulcrum: Fixed point of rotation about which the lever moves.

Load: The resistance or weight to be moved. The weight of a human body part to be moved is the load.

Effort: The force being applied that causes the lever to move. The agonist muscle in the human body.

23
Q

what is the load arm

what is the effort arm

A

Load Arm – The perpendicular distance from the fulcrum to the load.

Effort Arm – The perpendicular distance from the fulcrum to the effort.

24
Q

how are levers classed

A

Levers are classified depending on the component which sits in the middle of the three.

25
Q

example of classes

A

1st) nodding
2nd) calve raise
3rd) bicep curl

26
Q

which class lever has a mechanical advantage and why

A

2nd class levers have a mechanical advantage as the load lies between the effort arm and fulcrum. As the effort lies further from the fulcrum than the load it is more significant. This means a small amount of effort is needed to move a large load.

27
Q

which class lever has a mechanical disadvantage and why

A

3rd class levers have a mechanical disadvantage as the effort lies between the fulcrum and the load and as the load is further from the fulcrum than the Effort, it is more significant. This suggests the lever will struggle to move heavy loads in this manner.

28
Q

what is Limb Kinematics

A

The study of motion, limbs & movement…

Through video, motion or 3d analysis of technique we can improve performance.

29
Q

what is a kistler force plate

A

Rectangular Metal Plate, often used in combination with video/motion analysis.
Uses load cells/strain gauges to measure force.

The following can be calculated:
Force-Time
Acceleration-Time
Velocity-Time

30
Q

force plates are used for

A

To analyse gait/walking/running e.g. improve technique of marathon runner.

To analyse posture of e.g. improve persistent back pain of rugby player.

To measure/improve balance of e.g. to improve performance of swimmer on starting blocks.

31
Q

what are wind tunnels used for

A

Wind tunnels used to simulate air resistance.

Cyclists analyse performance to improve aerodynamics to increase speed.

32
Q

define velocity and give equation

A

‘The rate of change in displacement’

Velocity (m/s) = displacement (m)/ time taken (s)

33
Q

define momentum and give equation

A

The quantity of motion possessed by a moving body

Momentum (kgm/s) = mass (kg) x velocity (m/s)

34
Q

define acceleration and give equation

A 
The rate of change of velocity
Acceleration (m/s/s) = 
Final velocity (m/s) - initial velocity/time taken (s)
35
Q

definition of linear motion

A

Linear motion is movement of a body in a straight or curved line, where all parts move the same distance, in the same direction, over the same time’.

36
Q

linear motion is a result of…

A

Linear motion results from a direct force being applied to a body, directly to the centre of mass.

37
Q

define speed and give equation

A

The rate of change in distance’.

Speed (m/s) = Distance/Time Taken

38
Q

when does deceleration occur

A

Occurs when the rate of change of velocity is negative or there is a decrease in velocity over time

39
Q

what are the key descriptors of linear motion

A
  1. Distance
  2. Displacement
  3. Speed
  4. Velocity
  5. Acceleration/ deceleration
40
Q

define angular motion

A

‘Angular Motion is the movement of a body or part of a body in a circular path about an axis of rotation’.

41
Q

angular motion is a result of…

A

eccentric force being applied to a body, OUTSIDE of the centre of mass

The greater the eccentric force, the greater angular motion/momentum

This is known as TORQUE - a turning or rotational force

42
Q

Angular Motion is measured in

A

Radian = a unit of measurement of the angle through which the body rotates

43
Q

3 key descriptors in angular motion are;

A

Angular Velocity AM=A
Moment of Inertia
Angular Momentum

44
Q

define angular velocity and give equation

A 
the rate of change in angular displacement 
Angular velocity (rad/s) = angular displacement (rad)/time taken (s)
45
Q

define moment of inertia and give equation

A

Moment of Inertia is the resistance of a body to change its state of angular motion or rotation.

Equation:
Moment of Inertia (kgm2) = Sum of (∑)
(Mass (kg) x Distribution of Mass from Axis of Rotation(m2))
MI = ∑m x r2

46
Q

factors affecting MOI

A

Mass

Distribution of mass from the axis of rotation

47
Q

why does mass affect MOI

A

The greater the mass of a body, the greater the moment of inertia
A lower mass, decreases the moment of inertia and resistance to change of state of rotation
Sports with high degrees of rotation or twists/spins typically performed by athletes with lower mass

48
Q

why does Distribution of Mass from Axis of Rotation (m2) affect MOI

A

The further the mass from the axis of rotation (AoR), the greater the moment of inertia (and therefore resistance to change state of rotation).

49
Q

what is angular momentum and give equations

A

THE QUANTITY OF ANGULAR MOTION POSSESSED BY A BODY.
Equation:
Angular Momentum = Moment of Inertia x Angular Velocity

50
Q

explain Conservation of Angular Momentum

A

On a basic level, once angular momentum has been generated it doesn’t stop or change! Hence the term conservation)
Angular momentum is a product of inertia and angular velocity. Therefore if moment of inertia (MI) changes, angular velocity also changes.

51
Q

what is the analogue version of newtons first law

A

A rotating body will continue to turn about its axis of rotation with constant angular momentum unless acted upon by an eccentric force or external torque’. - Analogue Law

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