Revision Lecture Flashcards by Megan Eastham

What is a time series?

A measurement of something moving constantly at however many times per second.

Typically split into key events that show key parts of the movement

Events= key movements

Phases= the middle of key events

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Displacement equation?

= final position- initial position

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Velocity equation?

= change in displacement/ time

(m/s)

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Acceleration equation?

= change in velocity/ time

(m/s2)

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Momentum equation?

= mass x velocity

=kgm/s

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Laws of Motion- key parts of understanding for each law?

no change in momentum until a force changes it
F=ma, acceleration is proportional to the force and direction
equal and opposite reaction- Ground Reaction Forces

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Force equation?

= mass x acceleration (N)

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Weight equation?

= mass x acceleration due to gravity

= x 9.81

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Constant acceleration equations?

suvat

s: displacement
u: initail velocity
v: final velocity
a: acceleration
t: time taken

v= u + at

v2= u2 + 2as

s= ut + 1/2 at2

s= 1/2 (u+v) t

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Moment/ torque equation?

= force x perpendicular distance

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What does frame rate affect?

The blur produced when taking a photo

How many times the camera takes a pic per second

Increased frame rate= decreased blur
(but less light)- add unnatural light

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What does shutter speed effect?

The light produced when creating a photo

How long the shutter is open for

Less time= less light

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What is aperture?

The size of the hole of the camera

Bigger size= more light

But smaller= greater acceptable region you can film

= focal length/ diameter of hole

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What is focal length?

What distance away you are focussing on- can make the camera more/ less clear

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Define centre of mass?

A conceptual point where all the mass of a body can be concentrated

-Balance and CoG over Base of Support

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What factors affect passive stability?

-Increasing weight
-Increasing your base of support
-Increasing the horizontal distance from CoG to base of support
-Decrease height of CoG over base of support

What are aspects of stable equilibrium?

Potential energy is at a minimum
Work must be done to change position
Tendency to return to original posture

What are the aspects of unstable equilibrium?

Potential energy is at a maximum
Little/ no work needed to change position
Small movements will force gravity line outside the base of support

What are the aspects of neutral equilibrium?

Moves but no change in potential energy

Small base of support so doesn’t matter

What are the main modifiable factors to increase stability?

Increase mass
Keep CoG withn BoS
Increase BoS
Lowering CoG
Extend BoS towards oncoming force
Shift CoG towards oncoming force

Common balance reflex mechanisms?

Ankle strategy
Hip strategy
Stepping Response
Arm Circles

Forces within projectile motion?

Vertical force: gravity
Vertical Acceleration: 9.81m/s2

Horizontal force: 0
Horizontal acceleration: 0

Angular Displacement conversions?

360 degrees= 1 revolution= 2 radians

Angular Velocity equation?

= angular displacement/ time taken

(rad/ s)

Angular acceleration equation?

= change in angular velocity/ time =rad/ s 2

Moment of Inertia equation?

= mass x distribution of mass from axis of rotation = kg.m2

Angular Momentum equation?

= angular velocity x moment of inertia = kg.m2.rad/s

Evaluate the use of embedded force platforms?

Pros: Accurate and reliable 3D force measurements high sampling frequency and resolution Cons: restricted to indoor use and a single step Possibly unnatural gait pattern created- force plate targeting Expensive

What is a triaxial accelerometer?

Measures instantaneous acceleration at rest - will measure 1g due to gravity Usually used to measure- physical activity, intensity and "load" monitoring +ve- cheaper than lab equipment easy to use often embedded in other devices can monitor close to sight of intrest -ve- valid for intended purpose ? affect the movements being monitored? battery life and comfort?

Impulse equation?

Impulse (N)= FORCE X TIME impulse= change in momentum

Rate of force development equation?

Rate of force development= change in force/ time taken Force Development= VALR- vertical average loading rate - 20-80% VILR- vertical instantaneous loading rate- max

Define and give the equation for friction?

A force that acts in opposition to the movement of one surface over the other Friction force= friction coefficient x normal force

What are the main factors that affect drag force?

Dans, Van, Can, Swim Density of fluid Velocity- relative velocity Coefficient - drag coefficient Surface area- must be streamlined

Laminar flow?

Decreases resistance to movement -Fluid slides smoothly over -Layers flow in parallel -Little disruption to fluid

Turbulent flow?

Increases friction -less orderly/ predictable -greater impact on object- slows -boundary layer composed of vortices that increase surface friction

What are the three main ways that drag can be decreased?

- smaller surface area -slower relative velocity -more streamlined shape

What are the constraints to movement/ motion?

Movement Pattern- general series of anatomical movements that have common elements/ special configuration Skill- when a general movement pattern is adapted to a task Technique- when a skill/ task is performed Style- individual modifications- eg: individual timings Rules and environment- rules may guide/ penalise natural movement- discuss swing Human factors- strength, speed, genetics

What are the six steps taken when gathering information?

1. Determine the objective of the skill 2. Note any special characteristic of the skill 3. Study elite performances of the skill 4. Divide skill into phases 5. Divide skill into key elements 6. Understand the mechanical reasons that each element is performed as it is.